Stiles watches Derek die from aconite poisoning, black liquid oozing all over the floor when he retches until—until he doesn't anymore.
Stiles watches Derek drown in a pool, his body unresisting, swallowed by the water right along with his last shout.
Stiles watches Derek get shot through his throat with an arrow.
Stiles watches Derek burn inside a circle made of mountain ash.
Stiles watches Derek being electrocuted for so long that after it's done he doesn't even look like a person anymore.
Stiles watches Derek die and die and die over and over again because that's what Derek does in his nightmares, he just dies, keeps dying, and Stiles can't do anything to save him no matter how hard he tries.
Stiles watched Derek die every night for the past three months while Derek was gone to gods only knew where and to do gods only knew what, nobody knowing if he'll ever come back or even if he's safe.
Stiles watched Derek die and every night for those three months he woke up with tears glistening on his cheeks, heart pounding madly in his ribcage and blood rushing through his veins like he's on the verge of a panic attack.
(When Deaton told them that they'll always carry a piece of darkness inside their souls, Stiles was too scared and desperate to pay him any attention. If he did, he still wouldn't have thought that there will be a time in his life when he'd welcome a dream about his dead mother with relief and gratitude, when he'd choose it over the dreams he's having.)
When Derek comes back in the spring, Stiles punches him so hard he sprains his wrist.
Stiles watches Derek fall down form the top of a mountain he was climbing.
Stiles watches Derek being sacrificed by Jennifer, blood pooling around his ankles.
Stiles watches Derek choke to death on a bread crumble.
Stiles watches Derek get mauled by a pack of rogue wolves, and it's so absurd that he laughs hysterically for fifteen minutes straight after he wakes up.
He doesn't know what he expected to happen after Derek comes back, but it didn't happen at all.
"Are you getting enough sleep?" Derek asks when he sees Stiles for the second time since he returned to Beacon Hills. They're in Derek's new apartment, a small place with windows facing East and a reading corner in the living room, everything seeming less real in the light of the late morning.
"I'm fine," Stiles says—lies, really. He isn't fine, not by a long shot. Even his hands look tired when he glances at them, his skin pale and too tight around his knuckles.
He doesn't meet Derek's eyes when Derek stops slicing tomatoes to look at him over the countertop.
"You need to take care of yourself, you know." There's strange gentleness to his words that wasn't there before, not even after Boyd's death.
You need to stop leaving me behind, Stiles doesn't say. Tomato juice dripping from the slice he stole from the counter makes his skin sting where his cuticles are bitten raw.
Derek watches Stiles trash and scream in his sleep, watches him say brokenly, "no, no, please no," over and over again, watches him keen. Watches him repeat Derek's name like a mantra or a plea, and cry.
(He shouldn't even be here, but he actually had something he wanted to talk about, something he learned about when he was away. He decided to climb into Stiles' room like he used to on a whim, too, for old time's sake since the Sheriff is on the shift, and he didn't know.)
He's still frozen in place and devastated when Stiles wakes up sweaty and trembling, his hands flying to his face as if to try to physically contain his dream to the space behind his eyes. Derek can't help but count his breaths until they're steadier and deeper, can't help but feel for him. (He knows the taste of guilt and despair and loss.)
He switches on the lamp; it unsettles him how Stiles doesn't flail even a little. He should; that's what he'd do a few months ago.
They look at each other in silence for a long moment, none of them moving.
"I should be so pissed at you right now," Stiles says at last, his voice hoarse. "But I don't think I can muster any energy to actually shout at you. What are you doing here?"
"You dream about me," Derek asks like he's making a statement, ignores the question he deems unimportant.
"Yeah." Stiles' laugh is choked-off and weak. "You could say that I can't get rid of you even in my sleep." The skip in his heartbeat makes Derek pause and really look at him, instead of trying to burn a hole in the carpet with his eyes.
"Do I die in them?" he asks very quietly. He doesn't even need to hear Stiles confirm it for him; it's written all over his face. "How often?"
"Always."
Stiles' expression changes from fury to pain to something hard and unforgiving almost too fast for Derek to notice; he definitely doesn't understand.
"You always die, asshole, and it's always my fault."
Since then, almost every night when Stiles watches Derek die, Derek is there to latch onto when the nightmare releases Stiles from its clutches, and to soothe him with calm, patient presence.
It's been a year, and Stiles watches Derek get stuck in an apple tree.
He doesn't see Derek from the ground—too many leaves—but he does hear him curse at starlings that aren't afraid of his claws and eyes flashing blue. He can imagine Derek's t-shirt being dirty and ragged, branches catching on the cuts in the fabric, and it makes him grin like a loon.
(Stiles watches Derek get stuck in a tree and almost sees the starlings pick at Derek's bloody cheeks and eyes and throat; he shudders, all good humor lost.)
Derek senses his distress, picks one of the apples from the tree and throws it down right at Stiles' head. He considers Stiles' indignant yelp a win.
"Hey! See if I help you down, asshole!" yells Stiles, throwing the apple back and missing Derek completely (but almost not missing his own nose.)
"Careful, you'll give yourself a concussion!" he shouts back and laughs when the only response he gets this time is an annoyed huff.
"You're gonna stay in that tree until Scott takes pity on you," threatens Stiles. "And he won't do that because he likes me better."
"Whatever you say, princess," Derek agrees readily and throws another apple to the ground. "If not for me, you wouldn't have your apple tart dream coming true because Scott doesn't even like apples."
"Scott's a dick," Stiles mutters darkly, and it's obvious that he's already plotting his best friend's demise. Derek stiffens a chuckle. "Thanks," he hears after a moment; almost too quiet to catch.
"Always," he promises like he always does since that night when he found out about Stiles' nightmares.
He doesn't plan on breaking his promise any time soon.
When Stiles turns eighteen, he haven't watched Derek die for over two months.
That night he doesn't sleep at all, and even if Derek tells him that he will be the death of him, Stiles wishes really, really hard it won't ever be the case.
