It's the crispness of fall that reminds him. People think because it's over it shouldn't bother him, but the truth is, it's never over. The truth is, once it happens, they aren't the only one affected. You are, too. Because as crazy as their drug of choice makes them, you find yourself going crazy a little, too.
Every change in behavior is analyzed far outside of what is typical, even for them. When Reid is short with him, it doesn't mean he's having nightmares, or that he hurt himself or any of the other millions of excuses that it used to mean. Now, it means he's struggling. And when he struggles, so does Derek. Not because there's something between them. There's not, really. They're coworkers. Sometimes, they're friends. Now, he's not sure what the hell they are. Only that he's not the person Derek met years back. He's jaded. He's lost in a haze of his own making. And yet it's not. It's not his own making because addiction isn't his fault.
...But somewhere there's a choice, right? There's gotta be a moment when the decision to use or do anything else lies in Reid's hands. But the truth is, Derek doesn't know. This isn't his struggle. He's just an observer. Watching as his coworker - his friend - wastes away in front of his eyes.
Everyone's walking a fine line around Reid. Because it's his own business. Because the job can't find out, not officially. The thing is, it just feels so wrong to stand by and do nothing. And it feels wrong to get involved in the crazy of it all.
He wonders if it will ever pass.
The memories that fall brings with it... The destruction of a teammate they are forced to witness...