Imagine an AU where Derek needs touch to survive. It was all fine and dandy, he had his family when he was young, and he never even came close to dying because he went without touch for too long. There was just no opportunity given how big his family was and how tactile wolves are. But then they all burned and he only had Laura left, who also died a few years later.
And now he is in Beacon Hills and the only one who ever really touched him was Stiles, but he left for college a few months back. Derek has been slowly dying ever since because he is not really part of Scott’s pack and no one particularly cares to touch him.
Derek doesn’t tell anyone about this, because he knows what it’s like to be touched against his will and he wouldn’t want to force anyone to touch him when they really don’t want to. And he can tell that no one from Scott’s pack wants to touch him but they would if they knew what was going on, they would feel obligated even if they didn’t want to, and Derek isn’t about to do that to them.
So when Stiles comes back Derek is only a shadow of his former self and Stiles worries. And he worries and worries and does research and then one day he grabs Derek’s shoulder to stop him from walking away and Derek slaps his hand away and yells “Don’t touch me”.
Because dying hurts, but he is almost done now, and he really doesn’t care to go through the process again when Stiles leaves for college again.
Stiles on the other hand did some really extensive research and he saw how other packs worked at his university and there is always someone touching and puppy piles and scent marking going on and so he assumes that it’s the same in Scott’s pack and that Derek is dying because of all the touching.
So he tells everyone to stop touching Derek who doesn’t even protest because death is already so close, he can almost feel it, but the pack tells Stiles that there is no touching at all going on with Derek ever, which just leaves Stiles confused cause he thought he had figured it out and found a way to help Derek.