He's seen this before.
He's at the base of the ruins of Decarabian's tower. Chunks of the stone walls litter the ground, eroded by time and the wind; a beast roars from the top, the familiar sound filling him with fear. He forces himself to move, run, because if it's anything like the other times, he hasn't a moment to waste.
One foot into the tower, Kaeya ducks to avoid a blast of fire. The Abyss mages cackle as he runs past: there's no time for him to defend himself when his goal is the highest floor. He knows the layout well by now, and weaves between elemental attacks as he scales the tower. Dodging the missile barrage of a ruin guard, he leaps into a strong current and unfurls his wind glider.
And prays that today he'll be there in time.
A powerful shockwave from the dragon's roar nearly sends him plummeting, but Kaeya manages to grab on to a platform and haul himself up. Out of breath, he can only watch in horror as the scene unfolds.
The traveler and their fairy companion lie a short distance away, unmoving and disarmed. Jean, in the middle of casting her precious Dandelion Breeze, is sent flying by twin energy blasts. The bard cries out for her, using his anemo powers to launch himself out of harm's way and after his ally. Leaving his other ally to stand alone before the dragon.
Diluc's back is to him (again). His claymore ablaze, he readies himself for his next attack (no, no). Kaeya throws himself forward, using the last of his strength to create a barrier of ice (please be enough, please protect him).
His ice is nothing to the dragon. The rain of energy shatters it, then the platform beneath their feet. As he falls, he sees the surprise in Diluc's wide eyes, hears the cackling of the Abyss mages.
He failed again.
And he screams.
"-eya? Kaeya, wake up!"
He jolts awake with a gasp. The bed he's sitting on is not his own, the sheets too silky to be his. His vision is blurry: his eyepatch has slipped off. There's a hand gripping his shoulder and another squeezing his hands. Turning his head slightly, he sees ruby eyes and a mane of fire gleaming in the moonlight.
He's here. They're alive. He's safe.
Diluc's grip relaxes as he lets out a shaky breath. "Shit, Kaeya, I didn't think you were actually having nightmares that bad."
Those red eyes glitter with concern. There's a lump in his throat, his lips uncooperative; all he can manage is a small whimper. "Luc…"
"Shh, I'm here," Diluc soothes as he gently pulls him to his chest, curling around him protectively. Kaeya drinks in the smells of Diluc: fresh grapes and sweet smoke. Warmth chases away the chill he hadn't realized had settled in his bones; a hand combs his hair and he feels terribly nostalgic.
"Just breathe, Kae. I'm here with you."
Diluc's voice is deeper now than when he last spoke those words, but they echo within Kaeya nonetheless. He takes a few deep breaths, steadying himself.
"You used to say that a lot."
Diluc's hand pauses for a moment before leaving his hair. "You had nightmares almost every other night."
"Guess so," Kaeya chuckles, relaxing against the redhead. His gaze settles on their still-entwined hands, carefully easing his grip. When he looks up, the other is staring. "Hm?"
"It's nothing," Diluc says curtly, looking away, but Kaeya already knows what he saw. He finds himself averting his gaze too.
"It changed after I got my Vision."
"Yup. Lucky that was the eye I had covered already," Kaeya forces a little laugh, feeling the way Diluc tenses. Time to talk about something other than his cryo-blue eye.
"You're loyal to Mondstadt now, right?"
His breath catches in his throat. He spent years dreaming of the land that abandoned him and nights plagued by the one he vowed to protect, and Diluc asks him this? "Of course. I'll do everything I can to protect Mondstadt."
To protect you.
Whispers of the nightmare he'd so recently woken from creep into his mind, suddenly leaving him cold. He tangles his hands in the front of Diluc's nightshirt, pulling the redhead down with him as he lies back. "Come, let's sleep. I'm sure you'll be busy in the morning."
Diluc huffs. "And you?"
Kaeya thinks about the concern in Jean's eyes when she'd pulled him aside earlier that evening. He hadn't realized the toll the nightmares had taken on him until she'd ordered him to get some proper rest.
Diluc hums when Kaeya cuddles him again, waiting for him to settle down before wrapping an arm around his waist.
"Good night, Diluc."
"Sleep well, Kaeya."