Ever since Derek Morgan had met the ingenious Dr. Spencer Reid, he had always wondered just how many pairs of socks the younger agent had. Every day, Derek would steal glances at Spencer's feet whenever his pant legs were raised to peek at what pair of socks he was wearing on that particular day.

Today is no different.

Since they are supposed to be taking a break to work on case files and JJ needs to figure out which cases they will be working on next, they are all in the bull pen (save Hotch and Rossi, who are in their individual offices).

Derek looks over at Spencer as the man puts his feet up on his desk and crosses them at the ankles, reading through a file. Today, Derek sees as he leans over to see, Spencer has a white sock and a black sock. 'Like yin and yang,' he snorts in amusement.

Prentiss looks over at him, confused as to what he is laughing about.

Derek points over at Spencer's socks and Emily raises an eyebrow. "What?"

Derek frowns, wondering how she has not noticed their friend's odd habit in all of the time she has been part of their team. "Forget it. It's nothing."

But the questions stick with him throughout the rest of the day, as it begins to rain and the team makes plans to meet up at a Chinese restaurant for their dinner so that none of them have to worry about scrounging up a meal after a long day of paperwork: Just how many pairs of socks does Reid have and why does he never match them?

"Hey, Morgan," calls Spencer.

Derek snaps out of his thoughts and looks over at his friend. "Yeah?"

"Could you be my ride? I walked today and forgot an umbrella and I don't really want to get wet…"

Derek grins. "Sure, kid."

When the group finishes up their final work, they head out to the parking garage and get into their individual vehicles.

"We'll see you there," Derek says, waving at the others. He leads Spencer to the spot where he parked. He notices Spencer as he frowns down at the puddles on the ground, trying his best to evade them. Giving a devilish smirk, Morgan stamps in one, purposefully spraying his friend with the water.

Spencer sputters angrily, wiping a hand at his front. "Morgan! Great, now I'm all wet."

Derek laughs. "That's the point of rain, pretty boy." He unlocks the doors to his car and they both get in.

"Seriously, Morgan? Why'd you have to do that?"

Derek shrugs. "Cause I thought it would be fun."

Spencer groans. "Well could you at least take me to my place so I can change?"

Derek is about to protest, saying that the others would be waiting, but then he thinks about it. 'If I take him there… well, changing his socks would be a definite. I could finally get my questions answered…'

He grins. "Absolutely."

Puzzled by the eagerness in his co-worker's voice but pleased that he would be able to get dry, Spencer begins giving directions to his place, not knowing Derek's motive.

When they arrive, Derek follows him inside and Spencer steps into the bedroom to change while Derek waits in the sitting space. The door opens and when Spencer steps out—now wearing fresh pants and a sweater- Derek realizes he is still barefoot. He follows Spencer back into the bed room and to the drawer that Spencer opens and begins riffling through. Derek peers past Spencer's shoulder at the extensive collection of socks in the dresser. "You have one drawer dedicated to nothing but socks?" he asks, an amused grin tugging at his lips. He reaches past the other and plucks up a handful. "And it looks like only a couple of them are actually pairs." He holds up a striped one and a plain blue one that had been folded neatly together. Raising his eyebrow, he looks at his friend.

Spencer shrugs, the ends of his ears turning pink. "They get destroyed a lot, but there's no point in getting rid of both socks if one of them is still in good condition." He takes the socks from Derek and puts them back into the drawer. When he finds the pair that he had been searching for—a red one with black polka-dots and a pink one with white clouds—he sets it on top of the dresser and shuts the sock drawer.

Derek follows as Spencer sits down on his immaculately made bed and pulls the socks over his bare feet.

"How long have you been collecting them?" he asks, curious.

Spencer shrugs. "Since I was a kid. My mom and I didn't go out shopping much because of her… problems…" He frowns, then continues, "so I learned to make what I had last as long as possible."

"So that's why they never match," mutters Derek.

Spencer catches his whisper and nods. "Yeah, what of it?"

Derek shrugs. "I've just always wondered why you never matched your socks."

The genius stares at him. "Are you telling me that you soaked me and drove me here so that you could find out the reason why my socks never match?!"

Derek grins. "Of course not. The puddle just happened to be an accomplice for me teasing you; you're like a cat hating water and I couldn't help myself."

Spencer is still suspicious of his friend, but heads to his closet.

While Derek sees him looking for a dry pair of shoes, he sneaks back over to the dresser and quietly opens each drawer. The top drawer is shirts; the next is undergarments. But the third and the bottom two drawers are filled with even more incompatible socks.

He snickers. "You're kidding me! You've got three drawers dedicated to nothing but socks?!"

Spencer turns at his voice, a pair of shoes in hands and rolls his eyes. "Would you mind not going through my things, Morgan?" He pushes in front of Derek and forces the drawers shut, ushering the other man out of his room. He stands and puts on his shoes in the living room, then grabs his phone, wallet and keys. They leave his room and as they head down the stairs, Spencer says, "Oh, and Morgan?"

Derek stops. "Yes, Reid?"

"The next time that you want to know about one of my habits, just ask me, okay?"