Disclaimer: I do not own Life With Derek.

"You're getting… married?" Casey stutters out as she stares incredulously up at her step-brother. Derek nods eagerly, his smile widening with each passing second.

"Yeah, isn't it great?" He asks. "I woke up the other morning and literally thought 'Jess is amazing. So why not? She's literally the perfect girl for me.' So, I proposed! And she, obviously, said yes. I mean, come on, who would say no to Derek Venturi, right?" Casey's sure that the expression on her face must read as complete and utter shock. And she finds herself slightly glad for it because it serves to hide the fact that the man in front of her has basically ripped out her heart, torn it into millions of tiny pieces, stomped on it, and then spit on it for good measure.

"So, what do you think, Case?" Derek goes on. "By the way, Jess wants you to be one of her bridesmaids. I wanted you to be my best man since we're best friends and all but Jess said that'd be weird." Casey blinks and then shakes her head, clearing the jumble of screaming thoughts in her head, and finally forces the shock on her face away, replacing it with a forced smile.

"Wow!" She splutters. "That-that's amazing, Derek! Oh my God, yeah, I'd love to Jess' bridesmaid! Wow, you and Jess… that's… that's amazing." Derek's smile only grows and though Casey smiles back up at him on the outside, on the inside she feels like complete shit. She realizes then that she should have told Derek how she feels a long time ago. But she never has. And now she's lost him. For good.

3 months later

"Casey, are you alright?" Nora asks as she approaches her daughter and removes the cup of wine Casey had been chugging only a moment earlier from her hand. "You haven't said a word all night." Casey frowns, her gaze following the wine glass for a moment as her mom sets it aside. Casey sighs then, when Nora arches a questioning brow, and tries her best to muster up a pathetic looking smile.

"Sorry, mom," she apologizes, trying not to let the fact that she's completely miserable show. "I'm just not in a partying mood." She doesn't understand how she's fooling everyone with her fake act. She's been downing alcohol all evening and giving everyone snappy answers. It should be completely obvious that she's miserable. And why shouldn't she be? It's Derek and Jess' bridal shower and Casey's in love with the groom. It's almost hilarious.

"Honey, maybe you should go lie down for a while," Nora suggests softly. "You've had quite a bit of wine." Casey heaves a sigh but offers her mom another tiny smile when Nora frowns just the slightest bit. Casey nods then stands and stumbles her way out onto the back porch, assuring family members and friends that she's fine as they watch her trip her way outside until she settles on the wooden steps that lead out onto the backyard.

Casey stares up at the stars twinkling far up in the night sky with narrowed eyes. She can't believe she'd actually talked herself into attending the bridal shower. She had just graduated from Queens and she'd had big plans to move out to New York City and live with her dad for a while and get started on her dancing career. But then Derek had dropped the marriage bomb and screwed it all up. Casey had to stick around to help Jess plan the wedding to the step-brother Casey had been in love with for as long as she could remember.

Casey decides she hates Jess. Yet at the same time Casey knows she envies the other woman because Casey secretly wishes it were her inside the house with a smile on her face and a hand in Derek's arm, whilst enjoying the company of family and friends. But she's not Jess, the love of Derek's life. She's Casey, his step-sister, his best friend. She's the loser sitting out on the back porch steps hopelessly in love with a man who's getting married to another woman.

"Screw my life," Casey groans as she reaches up to run a hand over her face in frustration. The worst part is being a bridesmaid, she decides, having to look Jessica in the eye and pretend like she's ecstatic that Jess is getting married to Derek, pretend like she isn't jealous, pretend like she isn't completely in love with Jess' fiancé. Casey can barely stand to watch the two together. They really are perfect for each other and it makes her sick to her stomach every time she sees them together, which is pretty often.

"Casey?" a voice calls. Casey rolls her eyes when she recognizes the voice to be Jess'.

"What's wrong?" Jess asks, taking a a seat on the step beside Casey. "Why aren't you inside celebrating with everyone else?" Casey doesn't know why she does it, she thinks she'll blame it on the wine later, but she suddenly blows her top. She turns to Jess and outright scowls.

"I don't wanna celebrate, okay?" she snaps, her eyes filling with unshed tears and her hands trembling as the truth begins to pour out. "I-I'm not okay with this, at all! How can I be? I've loved him for so long now I can't even remember a time when I didn't love him! You think it's easy to just smile and pretend like everything's okay? Everything's not okay! I hate this! I-I hate you." Casey's voice breaks and her words trail off as Jess stares at her, horrified and speechless. Casey feels terrible right away. She's not this person. She can't be.

"I-I'm so sorry, Jessica," she hiccups, stumbling to her feet and backing away from the shell shocked bride-to-be. "I didn't want it to be like this. I just, I can't help it that I love him. I love him so goddamn much. I'm sorry, but I can't watch him marry you. I can't be your bridesmaid. I accept the fact that he's chosen you. I mean, why wouldn't he? You're perfect for each other. I just think it's time that I bowed out respectfully. I'm really sorry, Jess. I hope that someday… you can forgive me for this."

Casey turns and runs back into the house, the tears now flowing down her cheeks and clouding her vision, causing her to nearly crash into Derek in the hallway. She shoves past him and runs to the front door. Derek calls after her but she ignores it, ignores him and everyone else and throws open the front door. She runs out of the house blindly, she doesn't know where she's going. All she knows is she has to get away from Derek. From Jess. From it all.

Three weeks later

"Casey," Nora begins gently. "Are you really not coming to the wedding?" She and Emily stand by Casey's bedroom door and watch as Casey packs. Casey glances up at them and smiles softly. Her mother and friend are all dressed up for the big wedding and they look absolutely beautiful. Casey nods then returns her attention to packing. She's leaving. She's packed her bags and she has a one way ticket to New York City. No one except Nora and Emily know. Casey knows she can explain it to everyone else later over a phone call or something.

"Case, why don't you just tell him?" Emily cries out suddenly, stepping into the room with a desperate look in her eyes. "Come to the wedding! Tell him how you feel, how you've always felt!" Casey looks up at her friend with wide eyes, her heart pounding in her chest. Her mom is in the room! She glances past Emily, to her mom, and to Casey's utter amazement, the woman doesn't look the least bit taken aback.

"Mom?" she calls quietly, arching a curious brow as Nora sighs softly and makes her way over to her oldest daughter. Nora takes a seat on Casey's bed and pulls the bewildered young woman in for a hug.

"Casey, you're my daughter," Nora whispers into her ear before she pulls back only slightly to give her a smile. "I know you better than anyone else ever will. I've known how you feel about Derek for years now. I just… didn't ever expect it to come to this. I agree with Emily, you should tell him. He's so upset that you've been avoiding him. He doesn't know anything and he's so hurt that his best friend won't be there for him today." Casey feels her face scrunch up as tears threaten to well up in her eyes once again and she pulls away from her mom to wipe at them.

"Mom, t-that's exactly why I can't tell him," she stutters out. "I'm his best friend, his step-sister, that's all I'll ever b-be to him. I may be in love with him… but he'll always be in love with her." Nora frowns and reaches up to take one of Casey's hands in hers.

"Casey, listen to me," she begs. "If you don't tell him you'll regret it for the rest of your life. You'll always keep thinking back to the 'what if'. What if you had told him you loved him? You'll be haunted by it, never knowing what could've happened had you just told him the truth." Casey pulls her hand out of her mom's hold and wipes away the remainder of her tears.

"Mom, I love you," she says amidst sniffles. "But I'm sorry, I just can't. I belong in New York now, with dad and my career, and Derek belongs here now, with Jess." Nora sighs in defeat and nods before she stands and watches as Casey and Emily say their final goodbyes. When it's Nora's turn to say goodbye, she pleads with Casey to at least say goodbye to Lizzie before she and Emily leave for the wedding.

Casey knows her mom is right. About Lizzie. She drives to the church and parks her car along the curb just beside the building. Casey knows Lizzie will never forgive her if she leaves without at least saying goodbye. Casey breathes in deeply and gives her sister a call and asks the teenager to meet her outside the church. Lizzie runs out grinning.

"Casey!" She cries as she throws herself into her older sister's arms. "Did you change your mind? Are you coming inside?" Casey sighs and runs her fingers through Lizzie's curls for a moment.

"No, Lizard, I'm sorry," Casey says softly. "I just came to say goodbye to you." Lizzie's eyebrows furrow in confusion as she pulls away to stare up at Casey.

"Goodbye?" Lizzie questions, pulling away from her sister completely. "What do you mean?"

"I'm leaving, Liz," Casey informs her hesitantly, hoping her sister won't feel betrayed. "I have to go catch my flight to New York City and I wanted to say goodbye before I left." Lizzie's face falls as she gapes up at her sister.

"New York?" she sputters out. "But…Casey, you-you can't!"

"Don't worry, Liz," Casey tells her. "I'll be back for the holidays and I'll call you all-" Lizzie cuts her off, throwing her arms up and waving them around like a madwoman.

"No, Casey, you have to go inside!" she cries. "You have to tell Derek the truth. Casey, please!" Casey watches her sister beg with wide eyes. Why does it seem like everyone suddenly knows how she feels about Derek? Has she been that obvious?

"Oh, come on, Casey, everyone knows!" Lizzie cries out, rolling her eyes. "It's kinda obvious. I think he's the only one who doesn't see it. Hell, even Jessica knows! I heard her talking to her sister about it a couple weeks ago, said she wasn't sure about the wedding anymore 'cause of you and she felt like she and Derek didn't connect like you and Derek do. She was complaining about how he's always talking about you, telling her stories of you guys in college and she sees the happiness in his eyes. And the last few weeks he's been so depressed because you just disappeared and refused to come to the wedding. Casey, even Jessica can see what you two have! You two are the only ones who are blind!"

"Lizzie, I'm not blind, though," Casey tells her sister. "I can admit that I love him. God, I'm completely, a hundred percent in love with him… but he's getting married which means he doesn't see me that way, Liz. And he never will." Lizzie frowns up at her sister.

"Casey, just try, please!" she cries. "For me!" Casey feels her heart wrench in her chest at the sight of her little sister begging her. She bites into her lip then reaches out and pulls Lizzie in for another hug before she places a kiss on Lizzie's forehead.

"I'm sorry, Liz," she whispers into her sister's curls. "You'll understand someday. Tell Edwin, Marti, and Simon I'm sorry for leaving like this. I love you, Lizard." Casey pulls away and tries not to wince when she sees the tears welling up in Lizzie's eyes.

"I'll see you soon," Casey tells her gently before she turned and walks away, intent on starting a new life.

Lizzie's Pov

"Ed, please!" Lizzie begs, hands clasped together in front of her and practically on her knees as she stares up at her step brother with the best puppy dog expression she can muster up. "Help me!" Ed frowns down at the girl but then nods reluctantly. Lizzie grins victoriously and nearly jumps to her feet before she grabs him by the elbow and pulls him over to the door of the room where Derek and his groomsmen are getting ready in.

"We have to do this," Lizzie says, mostly to herself. "We have to tell him." Edwin rolls his eyes at his step sister and opens the door before following Lizzie inside. Derek stands in front of a mirror, attempting to fix up his tie with with a frustrated look in his eyes. When he notices Ed and Lizzie, he turns and offers them a small forced smile.

"Hey, Liz, what's up?" he asks, arching a brow at Ed as he does so. Ed and Lizzie walk right up to Derek and Ed places a hand on his older brother's shoulder.

"Derek, you might wanna sit for this, bro," he says dramatically. Lizzie rolls her eyes as Derek nods, a confused frown pulling at his lips as he moves to take a seat on the couch. Lizzie and Ed place themselves standing directly in front of him while all of his groomsmen stop and turn their attention to the siblings.

"Derek, I just saw Casey," Lizzie admits. Derek's eyes widen as he shoots up off the couch.

"What, where?" he asks frantically. "Is she here?" Ed once again puts a hand on his brother's shoulder and pushes him back down into his seat as Lizzie frowns.

"No, she was outside…a while ago," she tells Derek. He looks so confused, she almost feels bad for him.

"Derek, I don't know how to tell you this but she wouldn't do it so damn it, I'm gonna do it for her," Lizzie says, which just serves to make Derek look even more confused. So she takes a deep breath and stares her step brother straight in the eyes.

"Derek, the reason Casey refused to come to the wedding was because she didn't wanna watch you get married to someone else," she says quickly, all in one breath before she hesitates for a moment then goes on. "She loves you, Derek. She's loved you for so long. Since before Jessica, hell, since before college. She just couldn't tell you. She always thought, and still thinks, that all she'll ever be to you is your best friend" All at once, a round of 'finally' and 'about time someone told him' comments sound from Derek's friends.

"She told Jessica at the bridal shower that she loved you and she just couldn't be here today and watch you get married," Lizzie tells the groom. Derek blinks up at his step sister as he slowly processes the information.

"Casey… loves me?" he breathes out a moment later

"Yes!" everyone in the room nearly shouts at him.

"A-and Jessica knew?" Derek asks, frowning. "I asked her what had happened and she said she didn't know."

"She knew, Derek," Lizzie tells him. "I even heard her telling her sister she wasn't sure about this wedding because she knew Casey was in love with you and she said that it seemed like you loved her too. You just didn't know it. I heard her saying that she was so sick of hearing you talk about all the things that happened in college with you and Casey. She said that was all you ever talked about."

"Oh-ho yeah!" Sam calls out from in between Ralph and Dave. Derek shoots Sam a 'be quiet or I'll murder you' look and his friends all snicker at Sam. Lizzie rolls her eyes at all of them. Men are idiots, she decides.

"Derek, you have to tell me now, if you feel anything for Casey, at all, I need to know," Lizzie says, hoping to get everyone's attentions back. Derek looks up at her and arches a brow.

"Why?" he asks. Lizzie glances down at the floor before she says it.

"Because Casey came here to say goodbye to me," she tells him. "She's on her way to the airport. She's leaving for New York. Right now." When she finally returns her gaze to Derek, he's wide eyed and speechless. He remains that way for a moment or two before he finally snaps out of it and jumps to his feet.

"New York?" he all but shouts.

"Come on, D, go get your girl!" Ralph calls out encouragingly. Derek glances over at him, then his gaze sweeps the room.

"Everyone knows you wanna be with her, D,"another one of his friends calls out helpfully. Lizzie smiles at them, silently thanking them for their help as Sam walks up to Derek and places a hand on his friend's shoulder.

"Derek, man, I've been your best friend forever," Sam tells him. "I've seen how happy you are when you're with Casey and I've seen how depressed you get when she's not around. You may not realize it, man, but you love her and if you don't move your ass, you're gonna lose the only girl that'll ever love that ugly mug so much." Derek smiles up at Sam for a moment before he pauses and frowns.

"What about Jess?" he asks softly. "What am I supposed to tell her?" Surprisingly, Ed is the one who steps forward and looks his brother in the eye.

"Derek, you said she's the perfect girl for you but you know what?" he says. "The whole point of being in love with someone is to not be perfect, to have arguments, to fight, then makeup. To know that even though you're not perfect for each other you'll always have each other. Derek, you need your imperfect girl because she's the one who will always keep you on your toes. You need Casey, she's your imperfect girl." There's a long silence that follows and Lizzie almost swears she hears crickets chirping.

"Derek, please, go," she begs quietly.

"Yeah, come on, D, go get her," Sam adds on.

"Yeah, go, Derek!" Ralph shouts, and then all of Derek's groomsmen and closest friends, plus Ed and Lizzie, erupt into cheers, trying to get Derek to move his ass. Derek looks around at all of them, cheering for him and he grins.

"You're right," he says. "I gotta go, I need a car." Sam, Ed, and Ralph all step up at once and offer to drive him. Derek picks Sam at random and runs out of the room with Sam and Ralph in tow. Lizzie looks over at Ed for a second and watches him wipe imaginary dust off his shoulder before she frowns.

"What are we doing?" she cries out then, grabbing at Ed's arm. "We can't miss this! Let's go!"

Derek's Pov

"Derek, you're not supposed to see the bride before the wedding!" Jess' sister, Tammy, cries out as Derek bursts into the room where Jess and all her bridesmaids are.

"Derek!" Jess gasps when her gaze meets her husband-to-be's through a mirror's reflection. Derek runs up behind her and Jess turns to him, confusion etches all over her face. Derek can see Sam, Ralph, Ed, and Lizzie all standing just behind him in the reflection of the mirror, giving him encouraging looks.

"Derek?" Nora, who's helping a bridesmaid with her dress, calls, her voice dripping with a concerned tone. "What's going on?" Derek ignores his step mother only to get straight to the point with Jess.

"Jess, I care about you," he begins, nearly wincing at his every word. "I really do and I'm sorry that I have to do this." Jess seems to know what's about to happen because she sighs and nods.

"I'm sorry, Jess," Derek tells her softly. "But… I just realized… I'm in love with Casey. She's always been there for me, always, and I was too blind to see that she loved me."

"Derek, just… stop," Jess says, waving her hand as her shoulders slump in defeat. "I know." Derek raises an eyebrow down at the woman as she looks up at him and tries to smile through teary eyes.

"I was afraid you loved her this whole time," Jess tells him. "But I thought if we got married, you'd forget her. I should be sorry, Derek." Derek watches as she slowly slips off her engagement ring and puts it into the palm of his hand.

"Good luck," she whispers up to him. Derek can only stare down at her in awe. Jess really is an amazing girl, he decides, and she deserves better than him.

"Derek, her flight's in half an hour!" Lizzie cries out. Derek shakes his head and leans down to place a kiss on Jess' cheek.

"Thanks, Jess," he tells her before he turns and runs out of the church.

Casey's Pov

"Headed to New York?" the elderly lady standing in line just in front of Casey asks. Casey nods down at the woman, showing her the flight ticket.

"Yeah, just graduated from college," Casey tells her. "Headed off to the big city."

"I am too," the old lady tells her. "I'm going to my grandson's wedding, apparently he met the girl of his dreams. I'm so happy for him, he's so in love, you know?" Casey tries her hardest not to flinch and nods.

"Yeah, I do," she admits quietly.

"Oh, happily in love, are you?" the woman asks warmly. Casey lets out a small forced laugh.

"Not exactly," she says. The woman's face falls.

"Oh, well you know what they say, sweetheart," the woman says. "If he's the one for you, he'll be yours in the end." Casey thinks it's sweet that the woman is attempting to comfort her so she smiles down at the elderly lady.

"He's getting married," Casey tells her quietly. "At this very moment." The woman looks as if her heart's breaking for Casey.

"Oh, I'm so sorry," she whispers. Casey can do nothing but nod again and offer up a shrug.

"No, it's fine," Casey assures the woman, even though it's actually not fine at all. "I guess I'm just not the one for him, right?"

"You're wrong," a voice calls suddenly. The old woman's eyes widen as Casey freezes, not daring to turn around.

"You've always been the one for me, Case," Derek's voice says. "I was just too blind to see it." Casey forces herself to slowly turn around and meet his eyes. He looks a mess, like he's run all the way to the airport from the church. Sam, Ralph, Liz, and Ed are with him, standing a couple feet behind him, grinning like idiots.

"Case, you've always been the one that's always been there for me," Derek goes on. "That's why you've always been my best friend… I never thought you'd ever even think of me any other way. I'm not gonna lie, Case. I had a crush on you for a long time back in our first years at college but… we were best friends and I didn't wanna ruin what we had by telling you how I felt." Casey stares at him as he speaks, her eyes filling with tears and then overflowing and she wants them to stop but she can't.

"Then I met Jess," Derek says. "And she distracted me from you and all these years I was fooling myself into thinking I loved her when… it's always been you, Case. And I'm sorry it took me so long to realize it but… I'm here now, Casey and…" he trails off as he steps closer to Casey, stopping only a few inches away from her, making her tilt her head back to look up into his eyes.

"I love you," Derek breathes out finally. Casey's heart seems to jump up into her throat.

"I love you, Casey MacDonald," Derek tells her, grinning through his watery gaze. Casey tries to tell herself she's dreaming. But it all feels so real. And before she can stop herself, she returns his grin and practically buries herself into his chest as she lets the tears run free, her body shaking with sobs. Derek loves her. She can hardly believe it. But it's true. She can feel him wrap his arms around her waist tightly and she chokes on her sobs as she looks up at him.

"D-Derek, I-" she begins to say but Derek cuts her off, placing a hand at the back of her neck and softly connecting their lips.

Casey knows some people say they see fireworks, others say they hear church bells chiming or a chorus of angels singing but Casey wants to be be honest. She's not that unrealistic. When she kisses the love of her life for the first time, she's in a crowded airport and all she hears are the cheers of everyone around them as Derek holds her tight in his arms. All she feels is his soft warm lips pressed against hers and a joy in her heart that is so overwhelming, she thinks her heart might burst.

When Derek finally pulls away, after what feels like an eternity, Casey looks up into his eyes, grins widely, and finally summons up the courage to tell him what she's wanted to tell him for so many years.

"I love you so much, Derek Venturi," she tells him breathlessly. And Derek, in all his famed Derek Venturi glory, simply smirks down at her.

"Well, thank God, because if you rejected me after all of this, I might have thought you were crazy," he jokes. Casey just rolls her eyes up at him before she pulls him down for another kiss.

After all these years, Derek Venturi, her stepbrother, her best friend, is finally what she's always wanted him to be: simply hers.

Fin