I like to imagine that, if Zack had lived, he would have been so, so paranoid that something else was going to happen to Cloud.
He would find himself standing in Cloud's bedroom doorway, just watching him for a while, trying to make sure that Cloud is still breathing, that he hasn't missed any other effects of Mako Poisoning.
Zack wanted to stop being like this, but he just can't, he can't.
He had watched Cloud practically turn into a mannequin for months and months.
He's frightened he hasn't done enough.
Zack finds himself messaging Cloud a little more than normal, making sure he's alright, asking what time he's coming home.
He knows he gets too much sometimes, it's the main cause of arguments in the household between them.
"I'm not a child, Zack, stop checking up on me!"
Zack's heart squeezes at those words, because he knows Cloud is right.
Usually, Cloud just stares at him for a while, his eyes softening but his face still annoyed.
Zack rarely breaks down, but one day, seeing Cloud's eyes soften at him, breaks something inside of him and he has to pull the other man into his arms, crying loudly into Cloud's shoulder.
Cloud is alarmed, rightfully so, he's never seen Zack wail before.
But he quickly wraps his arms around him, despite being quite adverse to touching people (save for a few people, Zack included).
It's after an hour of them standing in each other's arms, that Zack finally tells Cloud why he's so protective of him, why he's frightened.
After confessing he's also having nightmares about Cloud being taken back to a lab, Cloud simply pulls him back into his arms, his hands placed tight against the back of Zack's head.
