It's the dreams that haunt him. Perhaps they're not even dreams; perhaps he sees these images long before he receives the luxury of finally falling into a restful sleep. They're more like flashbacks, only a little different.
They're as real as they can possibly get. He feels that full-body ache that comes with barely twitching a limb for half a decade. He feels the rain soak through his clothes. His grunts as he pulls himself along desolate, war-torn ground cannot be heard over the heavy downpour. It must've been decades since it last rained here. There was no reason for it ever to rain here. There was no life to sustain.
Except, now there was; on the edge of the cliff. That life was fading fast.
There's nothing in Cloud's head but an instinct to find Zack, to call to him, reach for him, protect him like Zack had done for him since the day they met.
By this time, Cloud usually wakes up from these nightmares, these stupid visions that he just can't unsee. This time, he doesn't.
He stays asleep, or maybe half-awake, in some zombie-like state, locked within the cage of his mind. He knows the worst of these flooding memories are coming. He's lived them many times before, every night, waking up in a cold sweat, not sure if the scream he hears is a sound he's actually making, or just another part of the nightmare.
It doesn't come. He waits, and waits, watching himself drag his broken body through mud and gravel. He barely remembers having to force his limbs to move, force his muscles to comply with his still mostly-dormant brain.
Finally, he's there. His tired eyes sweep across the torn being of his friend, his mentor, his fucking savior.
Only then does Cloud actually wake up, shooting upward from his bed, staring at the clock with wide, horrified eyes.
He can't escape this.
It hurts more than anything Cloud has ever known. It hurts more than being impaled by Massamune. It hurts more than being beaten up by those stupid little kids back home. It hurts more than the steely rejection in Tifa's eyes, more than watchig her fall down that mountain, more than not being able to catch her.
It's a different kind of pain, though. It's more than a sting, or an ache, or a throb. It's a fracture, but different from the kind you'd find in a leg or and arm or a skull. It's his entire body, a gaping wound across his very soul that no one sees, but everyone notices.
Slowly, so slowly, Cloud falls back until his head hits the pillow again. He doesn't close his eyes. He can't. He'll only see Zack's bloodied face behind his eyelids.
He'd only see the light in those eyes, fading fast.
He'd only be reminded of his helplessness.
The room is cold, unbearably cold. The bed's empty. There are no arms to hold him, no words to soothe him, no shoulder to let his tears fall upon.
There was only him.
There was always Zack.