I'M BACK. And with another Mortal Instruments-Infernal Devices crossover. :D After reading City of Lost Souls, it's sparked my love in the two series again! So, here's this story.

Jace gets some advice from an ancestor of his. ;D

Disclaimer: Cassandra Clare owns all characters. Lucky beeyotch. :P

Advice

"Don't act clueless, Jace. She was flinging herself, mostly her upper-body, at you and you just stood there!" Clary fumed as the two arrived at the institute.

They had just returned from Pandemonium, the night club, where one of the dancers- a "slutty stripper who had probably been 16 and pregnant at one point," in the words of Clary - had immediately zoned in on Jace.

"Honestly, Clary. I'm outrageously handsome. Obviously, other girls are going to hit on me. No big deal," Jace rolled his eyes as he trailed behind her.

"But you're also taken," Clary snapped.

"Why are you being so...pissy? Is it that time of the month?" Jace scoffed before realizing what he'd just said. Clary's wide set of green eyes flickered before reducing themselves to a squint.

"I'm being pissy because the guy I love is being grinded on by a ton of whores and he's just standing there, enjoying the view or something. I'm sorry, Jace Lightwood, that I'm not all boobs and ass like you want. I'm sorry I'm just not good enough," the redhead spat, although sadness was prominent in her voice. With that, she stomped up to her room and slammed the door loud enough for all of New York to hear.

"Clary-" he began before silently cursing himself. Reluctantly, Jace headed up to his room and drifted off to sleep.

"Your parabatai looks more like me than you do, and you're my descendent. Stupid genetics," a voice roused Jace awake.

Perched on his bedroom desk was a man with dark hair and piercing blue eyes, resembling Alec by a ton. He was dressed as if he'd casually traveled from London's 1800s to this century, top hat, long coat, and all.

"Who are you?" Jace groggily asked, inching closer to the seraph blade on his bed.

The guy strode over to Jace's bookshelf, picked up his "A Tale of Two Cities" book, and flipped to the inside cover. There was writing from a Will Herondale, one of Jace's ancestors, on it.

"I'm that guy," Will grinned, pointing at the inscription.

Jace blinked rapidly and really stared at the stranger. They did vaguely look alike, from the chiseled features to the smirky mouth.

"Why are you here? And how is that even possible?"

"You're dreaming, one of the more effective ways to contact family members from the past. And I'm here to give advice," Will shrugged, returning to his sitting position on Jace's desk.

"Advice...?"

"Girl troubles. Always been an issue for us Herondale's. By the Angel, I had plenty of those," sighed his ancestor. Will had a reminiscent look on his face full of heartbreak and love.

Jace blinked. "Girl trouble."

"Don't act stupid. You and Clary are in a fight, right? She's jealous and you're acting like an ass in response. Pride is another issue our family has had," Will smiled knowingly.

"It was some girl at a night club throwing herself at me. What was I supposed to do, slap her with Izzy's whip? Besides, Clary knows I love her."

"She may know, but sometimes, people need to be reminded. Also, jealousy is a terrible feeling. I've felt that many times. Just say sorry to her."

"But how? She won't even listen to me!" Jace pleaded.

"Did you hear what I just said? I swear, listening is another skill our bloodline lacks. I guess our handsome looks compensate for it. I digress. But, yeah, remind Clary you love her, and you two will return to being the most odd couple out there," Will winked.

Jace nodded thoughtfully. He looked up and asked, "Okay, but how do you know this stuff? Were you ever in love? As in, you'd die for this girl?"

Will laughed. "Jace, I'd die a painful, torturous death for her. Hell, I'd pet a duck for her, and Raziel knows how much I hate those things. Tessa... She was my one and only. Beautiful, strong, hilarious, powerful. Too bad I pushed her away half the time I knew her. My biggest regret. I hope you and Clary don't end up like that." Will squeezed his eyes shut.

"Well, thanks for the advice, Will. Can I wake up now?" Jace sighed.

"Oh, you will, in 3...2...1..."

Jace shot up from his bed and ran a hand through his tousled hair. "Remind Clary that I love her. Challenge accepted."

Clary attempted at sketching a simple apple, but due to frustration with everything going on, it ended up as a crude, scribbly circle.

A light knock turned her attention to the door. "If you're Isabelle, no, the glitter has not come out of my hair yet."

The door inched open, revealing a golden eye peeking through the crack. "I'm not Isabelle, and this isn't what I came up for, but I recommend Magnus's glitter-removal shampoo. Worked for me. Now, can I come in?"

"I don't know. Can you?" Clary retorted.

"Yes, I can." And, with that, Jace padded over to Clary in three long strides, grasped her delicate face in his fingers, and pressed his lips onto hers.

Clary made a noise of surprise, but, eventually, leaned into the kiss, relaxing her muscles. She broke away. "That was nice. But I'm still mad at you."

Jace sighed and pulled her toward him, wrapping his strong arms around her waist.

"You want to know why I just stood there? Because it didn't matter; the grinding or the dancer. All I saw was you. Ever since I've been with you, women swooning have been practically invisible. The only person that I care swoons over me is you, Clary. Only your opinion matters. Only the girl that I love from Idris and back matters. I'm sure you realized this already, but, I love you, Clarissa Fray."

"Okay."

"'Okay' as in I'm forgiven?" Jace smiled hopefully.

"You're forgiven," Clary laughed. She reached over and tugged Jace toward her, pressing her cheek to his chest. His heartbeat was strong and steady, just like him. "This is surprising. It usually takes a few more hours for you to apologize."

"Let's just say I got help from a relative," Jace replied, his voice muffled from nuzzling his face in Clary's hair.