Sisterly Interference by spikescrypt

Derek turns his head as his sister's screeching laugh fills his ears. He was in the middle of lifting weights; trying to release some of the tension he constantly feels coursing through his body. He spots her sitting on the floor of the loft with her back against the wall, fingers rapidly texting.

"Do I even want to know who is making you cackle like a witch on Halloween?"

Cora sticks her tongue out at him, phone gripped tightly in one hand.

"I'm talking to Stiles," she answers.

Derek frowns. "I didn't realize you two were so close."

"He has this sort of nerdy charm, doesn't he?" Cora grins. "Plus he has this wicked sense of humor."

Derek grunts.

"And those eyes," Cora continues, much to Derek's dismay. "They seem completely innocent at first but you can tell there's something beneath the surface. Something wild."

Derek accidently drops the 230 pound weight that he was flexing right onto his left foot.

Cursing Derek goes to get a bottle of water from the fridge while simultaneously trying not to limp.

He barely succeeds.

Also, he can hear Cora's body shaking as she tries to hold back her laughter.

Sometimes having a little sister is extremely bad for his health.

"Cora, is there something that you are planning to tell me?"

"Such as?" she asks.

"Are you and Stiles planning on eloping and running away together? Cause I'm pretty sure the Sheriff will drag both of your asses back."

Cora snorts, "I'm just saying the guy is cute, witty, and has saved both of our asses numerous times."

"Get to the point," Derek pleads.

"He's a catch," Cora says.

Derek sighs. "So you want to date him."

Cora sighs back. "God can you even be any more obtuse? No you idiot, I want you to date him."

"WHAT?" Derek shouts.

"You should date him," she repeats.

"You cannot be serious."

"Why not? You clearly have terrible taste in women as judged by your previous relationships with a werewolf hunter who killed most of our family and a psycho Druid wannabe who murdered half the damn town."

"Jesus Cora," Derek wonders who he pissed off to deserve this.

"Look, why not just try the less fairer sex and see if it's something you would enjoy."

"You're actually serious about this," Derek says. "You really want me to date Stiles."

Cora narrows her eyes at him. "Of course I'm serious. The guy clearly has the hots for you as demonstrated by the stench he gives off every time you look, speak, hit, or grunt at him."

"We are in no way shape or form continuing this conversation," Derek commands.

"Don't be such a prude," Cora argues. "I know you've checked out that fine tight ass before."

"Nope, nope, nope," Derek covers his ears immaturely. This does nothing to block out his sister's words. Sometimes having super werewolf hearing sucks.

"I bet Stiles could get you to lighten up and have some fun."

Derek glares at his sister. "What makes you think I don't have any fun? This conversation for example, loads of fun. I just might pass out from all the fun I am clearly having."

"Oh Derek, don't you want some sort of happiness in your life again?"

"I have you again," he says.

Cora smiles brightly at him and gives his shoulder a squeeze. "That's sweet and as glad as I am to have you back too you need someone besides me who you can be yourself with. And whenever I see you and Stiles together you act more and more like your old self. Maybe a more annoyed self but still you. "

Derek can't argue with that, Stiles never backs down from him and it makes him push back. Stiles isn't afraid of him and so they both continually push each other's buttons with no resolution in sight. What if they did have a way to resolve the tension? What if they ended all those arguments and insults in bed?

Cora wiggles her eyebrows at him and he flushes at having been caught in impure thoughts.

"All I'm saying is if Stiles wants you to tie him to a bed and let you have your way with him you should go for it."

Derek groans, whether from the image or because it came out of sister's mouth he isn't sure.

"Is it the Sheriff that you're worried about? Because it's not as if a regular gun can kill you, just stings for a while."

Derek rolls his eyes, stings his ass.

Cora's phone beeps signaling another text message and Derek watches with open curiosity as she reads it.

"Ohhhhh, he asked how you are," Cora teases.

She types a response that Derek cannot see.

The phone beeps again; Derek seriously considers pulling it out of her hands.

Cora glances at Derek after reading the message and giggles. Giggles!

"Tell me what you're saying about me," he demands.

"I just told him that he gives excellent mouth-to-mouth. Which I would know since he gave me CPR and that you wouldn't mind it if he gave you some pointers."

"Cora, I am going to rip your throat out. With my teeth," he threatens.

"Save that aggression for when Stiles comes over big brother."

Derek's eyes go wide. "Wait, you invited him over?"

"Should be here in ten minutes," Cora confirms. "You might want to put on an actual shirt. Or wait, actually no leave it off, Stiles will prefer it off."

Derek looks around in a panic. "I don't know if I should entertain this delusion you have or run screaming for the hills."

"Just because it's called Beacon Hills doesn't mean there are any actual hills," Cora taunts. "Besides if you two are going to make bunches of Stilinski babies you need to actually see the boy."

"That's biologically impossible."

"Whatever Derek, oh here he comes."

Derek gets a glimpse from the dark window of tight jeans and lean legs before there's a knock on the door.

Cora and Derek glance at each other, then at the door.

"Here we go," Derek thinks.

...

Stiles walks in with his hands buried deep in his pockets.

"So, I like what you've done to the place," he says glancing around at the mostly empty space. This was the first time he's visited the loft since Derek and Cora returned from their trip to New York.

"No point in making it look like an Ikea when there are always so many dead bodies to clean up," Cora says.

Stiles frowns. "No, I suppose not."

"So Stiles, save the life of any more damsels in distress lately?"

"Tragically you are the last damsel that's needed my lip services."

"That's too bad. I was just telling Derek how talented you are when you put your mouth to work."

"Cora," Derek warns.

"What? Don't you want Stiles to teach you how to blow?"

Stiles makes a chocking sound and he rubs the back of his neck nervously. Derek's eyes seem to track the movement.

Cora smiles predatorily.

"Um, you said something about finding a book on kitsune's?" Stiles asks distractedly.

"Did I?" Cora smacks herself on the forehead. "Silly me, I completely forgot that I gave it to Isaac. I'll just go over to Scott's and get it."

"I could drive you," Stiles offers.

"No," Cora says firmly. "You and Derek do some of that awkward glaring thing that's just flirting in disguise that you two do so well."

Cora walks out of the loft humming happily to herself.

"Well that was weird and that's speaking from a guy who spends his time running after lizard people and demon wolves, I know from weird."

"Cora seems to be under the impression that our relationship isn't purely platonic," Derek says matter-of-factly.

Stiles eyes grow wide. "You don't say. How not platonic are we talking here?"

"She seems to think that we should date."

"Huh." Stiles taps his chin. "I can see that."

Derek breathe catches. "What?"

"Well yeah dude, we sort of make sense in some freaky ass way. I mean we kind of have the teamwork thing down by now. We've saved each other's life too many times to count at this point."

"So just because I've saved your sorry ass you'd consider dating me?" Derek doesn't know if he should be insulted or concerned that Stiles has such low standards.

"Nah man. That's not….. Look you know when we're fighting together and everything's going to hell and then our shoulders will brush and there's sort of this spark of electricity?"

Derek nods begrudgingly; he's felt the electricity before. He's always just brushed it off as being from the heat of the moment. "Well maybe there's more to that then just adrenaline and you know hormones," Stiles cringes. "Maybe we should see if we can replicate that feeling when it's not life or death."

Derek is suddenly very interested to see where Stiles is going with this. "What do you have in mind?"

Stiles smiles. "Well, Cora was saying something about how I could show you some mouth-to-mouth."

"Really? Cause she told me that I should just tie you to a bed and do as I please."

Stiles flushes red. "Well maybe I'll tie you to a bed then."

"Wouldn't be able to hold me," Derek says.

"I could get a pair of my dad's cuffs."

"There's a bed upstairs," Derek offers.

"Race you," Stiles says running for the stairs.

...

Upstairs Stiles is running his hands slowly over Derek's hips. "I am so glad you walk around without a shirt on."

"I was lifting weights," Derek shudders as Stiles' hand dips below his waistband.

"Mm I wouldn't mind seeing that sometime," Stiles kisses a spot on Derek's neck and Derek grabs roughly onto his hair.

"Do we have to run this by Scott now that he's Alpha?" Stiles questions.

"I'm more worried about your dad actually," Derek answers.

"Don't worry. He won't shoot you; he might just rough you up a bit." Stiles finally leans in and he and Derek kiss one another on the lips for very the first time. It's hot and needy and they do indeed feel that electricity coursing through their veins, only this time it's not during a life or death situation.

"I look forward to it," Derek says. He's never been so thankful for some sisterly interference.

FIN.

P.S. - My alternate title for this would be: My Sister Was Right About The Flirting

Author's Note: If anyone is interested I started posting my Teen Wolf fics to Archive of Our Own under the same username of spikescrypt. Look me up! Also, if there is anything that you want me to put on my profile page on this site let me know. Maybe you want to ask me what my favorite pizza topping is or who I think the hottest Teen Wolf dad is. Whatever you want to know just leave it in a review or a PM and I will probably post the answers. Thanks, hope you enjoyed the story.

P.P.S. - If enough people really want me to write what happens later on when Cora returns I might consider it.