Stiles doesn't know how he hasn't noticed it before but Derek certainly changed. A least a little bit.
He is not as jumpy anymore.
Maybe it's because he got used to the pack or he is just more at ease with people around him in general. And instead of thinking of traps and treasons the alpha thinks about... something different.
Stiles doesn't know the 'whys', he just noticed the 'is' and that is an accomplishment alone.
Derek isn't as growly anymore.
Sure, he grumbles and rumbles but it's less aggressive. It subdued to an undertone where Isaac isn't scared of it anymore and Scott quit bitching. Stiles thinks Derek grew a little softer and also learned to adapt to his pack more. Like, Derek now puts effort into getting to know them better and adapt his behavior around the betas.
Derek is more of a playful sourwolf now, not a complete grump.
Although he remains the king of the Eyebrows Of Doom forever, Derek uses them differently nowadays. It's more in a teasing kind of manner than expressing a negative feeling or stand. Stiles likes to pretend talking to them. The best part is, that Derek let's him.
Derek allows his shoulders to relax on movie nights.
And he is actually showing up to those nights. Scotts eyes nearly fell out of their sockets the first time Derek settled in his armchair and watched a full time movie along with his pack. Stiles thinks that Scotts reaction was over the top considering that they were having the movie nights in Dereks loft but he has to admit he was surprised as well. It took four more movie nights for Derek to start some simple commentary that had the pack giggling and Erica topple over with laughter. He hasn't missed one since that and the pack is as close as ever, including the alpha.
Believe it or not, he developed a 'fond' smile. An almost smile with just the corners of his lips lifting up and a hint of smilelines around the eyes that could be there if his mouth shifted just the tiniest bit more. Stiles wished every time it happens for it to never stop and simultaneously to just grow that bit wider. He just wants to see a real, wide smile contorting Dereks face in the best of ways. And Stiles should really stop ogling Derek when he is smiling but he simply can't help it.
Something perhaps only Stiles has noticed is Derek treats himself. It's just quite, short moments - like bathing in the sun for a couple of minutes, wearing cozy socks and comfortable clothes, drinking hot chocolate on a rainy day or simply relaxing with a thick, dusty book on his couch - but Stiles feels incredibly proud. It took a long time for Derek to be comfortable enough with his surroundings to relax and even longer for him to be at ease with himself enough to let go of the stiff, defensive posture. He finally gets to enjoy himself and the surroundings he build and Stiles thinks, Derek deserves to be comfortable and happy with himself the most.
He started talking more about his feelings.
Well, it was one sentence but it got the point across pretty well.
It was on one of those rainy-evening-hot-chocolate-cozy-socks moments that Stiles got to share more and more often with the local alpha.
Stiles mumbles - the atmosphere is too calm and cozy to destroy it with loud talking, even Stiles gets that - on and on, about his day, Harris, some tittle-tattle from the police station, star wars. Derek sits opposite of him on the soft recliner, his knees bend comfortably, a white steaming cup between his hand and listening. Actually listening, like what Stiles rambles about is important or interesting. Stiles really appreciates that but it throws him off-guard at the same time and his words stop flowing. They are left looking at each other.
So Derek looks him dead in the eye when he says "I really like you, Stiles".
Stiles waits a few seconds for the 'but' that doesn't come and he has to swallow before he can answer.
"I really like you too, Derek." Derek smiles the tiny bit more that he usually doesn't and there they are - smilelines. He looks gorgeous with them.
"You should smile more often.", Stiles blurts out and his cheeks heat up instantly. "Not that you don't. I noticed that you smiled more and looked happier in the last few months but you never smiled like this. Like, enough to make your smilelines show. It looks good on you. I mean, you look good, always, but your smile is like the cherry on top and yeah... I like it."
Dereks expression changes from the happy smile to a fond one. It's somehow even better and Stiles preens, proud that his verbal vomit could trigger a reaction like this.
"I like that about you, having you heart on your tongue and being unapologetic about it. It's... endearing."
"Really? Nobody likes my rambling."
"It represents how honest you are. I like that. And your voice."
Face heating up further, Stiles mumbles a thanks and gets the happy smile back in return.
"Stiles?", Derek says after a few seconds of comfortable quietness. He places his half-full cup on the table in front of the couch.
"Yeah?", Stiles answers, looking at the werewolf from under his thick lashes.
Stiles scrambles over to Derek and into his open arms. It takes a minute for the both of them to get comfortable but in the end they lie snuggled together, Derek on his back, his head resting on the armrest of his couch and Stiles between Dereks legs, his head having found a home on Derek chest. Together they listen to the comforting sound of raindrops hitting the windows until Stiles lifts his head from its place over Dereks heart and looks at the alpha. "Can I kiss you?", Stiles asks. Dereks answer is leaning forward until their lips meet.