Warnings: Discussion of character death and brief mention of cancer. It is far fluffier than it sounds.

Notes: Written for teenwolfkink. While this was originally planned as a oneshot, there's now a (much happier) sequel in the works whenever I get around to it. :)

"Can you get those books for me? Top shelf." Stiles waved in the direction of his closet without bothering to turn away from his computer. Derek huffed, but Stiles was actually doing him a favor so he didn't complain about hauling himself off the bed to do as Stiles asked. The shelf, just above his eye level, forced him to skim his hand in the darkness.

Derek hit something rectangular and pulled it down. The object was lighter than he expected; he fumbled and dropped it. It – a lidless shoebox – hit the ground sideways and spilled several envelopes across the rug. Derek glimpsed his own name scrawled on one in Stiles' handwriting.

"What's this?"

"Wha-" Stiles turned in his chair and caught sight of Derek plucking the envelope from the box. "-Aah, no, that's not yours!"

"It has my name on it," Derek said as he turned the envelope over, finding it carefully sealed. It was heavy and nearly a half-inch thick, like there were multiple sheets of paper folded inside.

"Different Derek." Stiles' heart was all over the place as he dropped to his knees and gathered the rest of the envelopes up. "My life's not all about you, you know. Give it back."

"Different Derek Hale?" he asked, but Stiles actually sounded upset so he gentled his voice as much as he could.

Stiles held out his hand and made a 'gimme' gesture. "Different Derek Hale. Derek Hale in case of my untimely - or, well, probably just on time - demise. It's not yours yet."

"You wrote letters in case you die?" Derek just raised both eyebrows at this new strangeness from Stiles.

"Well, yeah. I mean - it's pretty likely, right? What with the werewolves and the hunters and the lots and lots of guns suddenly involved in my life -"

"Stiles."

"-And hey, if that doesn't get me by the time I graduate, my mom died from a disease pretty well known for being genetic, so, yeah, probably fucked."

Stiles said it easily, with no particular dread of the idea that he might die before he turned eighteen. He sounded more upset about Derek finding the letters than about dying. In fact, Stiles looked amused now that he had the box and most of the letters back in his possession. Derek watched as he retreated back across the room to his chair and pulled his legs up to his chin.

"Anyway, it's not a bad idea for everyone to have their shit together with a living will and organ donor card and DNR. Just in case. Being a vegetable for years would suck, I mean, look what it did for Peter's personality, right?"

"Stiles!" It was only when Derek saw Stiles staring back at him, wide-eyed, that he realized he'd shouted this time. Both of them were silent, Derek listening in to make sure the Sheriff wasn't headed up the stairs, before Derek backed down. He hunched his shoulders against the idea of Stiles' death and felt more shaken than he should, but Stiles accepted the gesture as a submissive one.

"Stiles," Derek repeated. "You're not going to die."

Stiles' eyebrows rose. Derek swore he could see the argument forming in Stiles' brain, so he cut it off with a correction: "You're not going to die iyoung/i. Between Scott and me, your idiocy is survivable. And - there's always the bite."

Derek knew he shouldn't mention it, but that didn't make it less true. If Stiles were hurt or smelled too sick, Derek didn't know if he would even give Stiles the chance to say no.

Though he looked like he wanted to argue, with his stiffened shoulders and his open mouth, Stiles stayed quiet. Instead he took a moment to collect his thoughts and then switched to a different track: "Fine, whatever, but it's better to be prepared. I don't want to leave things open-ended, you know? My mom, when it got really bad, started writing these really long letters to me and my dad and everybody. She wrote two to me, one for when she died and one for when I turned eighteen - that one's in Dad's gun safe. And it didn't really help but ... I don't know. I just want to say goodbye, if I can. And my dad deserves an explanation."

Derek realized this was the most meaningful conversation he'd ever had with Stiles, and he had no idea what to say. His mind blanked out. All he could think was: "What could you possibly have to say to me that takes this many pages?"

Derek tried to imagine what he'd tell Stiles in the same circumstances, and dismissed the first thing that floated to the surface because that would be cruel. Except-

Except Stiles licked his lips and looked at his - ridiculous - hands. "Lots. I would have lots to tell you. Stuff I can't say."

Derek was afraid to ask. He asked anyway. Stiles fidgeted in his chair, spun it left and right as if that would distract Derek. Derek waited until he realized Stiles wasn't looking for words so much as planning not to answer. He stalked across the room. He put his hands on Stiles' armrests, arresting the movement of the chair and forcing Stiles into stillness. He glared.

"Stiles. Say them."

Stiles' eyes tracked Derek's lips. Derek thought he might get his answer sometime tonight, but then Stiles said, "Derek, I can't."

He sounded regretful. Derek grimaced, let his frustration pour out in the form of bared teeth and drawn eyebrows. Stiles' scent and heart remained steady, a mile of progress from last year when Derek could still scare him into submission with a look. Stiles' trust meant something, but his stubbornness did nothing to ease Derek's frustration. "You wrote it."

"For you to read when I'm Idead/i." Stiles tilted his head back and Derek followed the line of his neck. His mouth felt suddenly dry.

"I don't want to wait that long." He wanted Stiles now, all of Stiles.

This time, Stiles' heart rate picked up and soared. Derek's hand left the armrest so that he could press it, palm flat, over Stiles' chest. Stiles stiffened, froze everything, even his lungs stuttered in protest. They hung like that and Derek realized he could move forward a few inches –

-But Stiles put his feet down, literally, and pushed the chair back into the wall and away from Derek. "I can't."

"Can't or won't?"

"Can't. Not yet, Derek. Please." Please. Like Derek would press while Stiles said no. He wouldn't. He put the letter down on Stiles' desk, propped it between monitor and keyboard, and nodded.

"It's okay. We have time."