With Castiel living with Dean for the indefinite future, one thing becomes clear to Dean: he absolutely can not be in love with his best friend.
The last thing he needs is to complicate Castiel's life. They've just become friends again, and Castiel is fragile. Castiel needs stability. He isn't in love with Castiel. He can't be.
It's just his poorly suppressed mother hen instinct. He's supposed to be watching to make sure Castiel is fine. If he's over-eager to help him eat, wrapping his hand around Castiel's too-cold, too-bony ones, it's because his friend has been through a lot and Dean needs to be there for him.
He tries to give Castiel is space because that's the most important thing. Castiel has a thing against people watching him or touching him or being in the same room with him while he sleeps. Dean listens for nightmares, but he doesn't know what to do one night when Castiel wakes up screaming, loud and panicked. He makes a mad dash for Castiel's room. His first instinct is to grab Castiel and whisper soothing things to him, but that doesn't work.
"Let me out! Let go, please. I won't tell, let me go. I want to go home."
"You're at my house, Cas. You're not there anymore. It's me."
Dean can't listen to Castiel's pleas. The soothing doesn't work, and he's not going to slap Castiel. So he pinches his arm.
Dean's surprised it makes Castiel come back to reality.
"Dean?" Castiel's dazed eyes find Dean.
"Yeah."
Castiel collapses against Dean and starts shaking uncontrollably. He's not crying, only trembling, and that somehow makes it worse. Dean wraps his arms around Castiel.
"'ts OK," Dean murmurs. There are times when Castiel doesn't mind physical touching, and this is one of them. "It's gonna be hard for a long time, Cas, but I'm going to be here."
He gently eases Cas back down, still clinging to each other, and Castiel falls back asleep.
Dean watches him for the night. Cas doesn't have another night terror.
The next morning, Sam lets himself in. He doesn't have class and whenever he can, he visits his family. He walks down the hallway, the door to Castiel's room ajar. His brother his half-spooning, half-restraining Castiel, but Castiel looks peaceful, comfortable.
When Dean wakes up later, he finds Sam in the kitchen.
"G'morning," he mumbles, rubbing his head and pouring himself coffee.
"Sleep well?"
Dean shrugs noncommital.
"I saw you and Cas. I know you didn't do anything, but Dean, you have to be careful."
Now fully awake, Dean pounds his fist on the counter. "Dammit, Sammy, I did what I had to to get him to sleep."
"I know. But please be careful, OK? Not just for him."
After that, Dean is careful. He doesn't give a shit about not getting his heart broken, but Cas needs a safe environment to recover. Dean needs to uncomplicate things for Castiel as much as possible. Maybe one day down the road, they'll have a nice life together. Maybe in another world, the year they spent not talking (Castiel bound up in a psycho's dungeon for almost half of it) could have been spent in a relationship. Or maybe Dean isn't in love with Cas and it's just some Florence Nightengale shit fucking things up.
One night, Bobby comes over for dinner. He's been a firm believer in sucking things up and carrying on with life after bad experiences, but Castiel can tell this whole thing has jostled him. He smiles too frequently for things to be normal, his voice is too quiet when he talks to Castiel, his eyes are too soft. These changes are subconscious, Castiel supposes. Bobby can't help it, so Cas doesn't let it bother him.
"You wanna hear about the case?" Bobby asks over a burger. "It's good news."
As long as Frederick can't do what he did to anyone else, Castiel doesn't care how harsh his punishment is. The damage is already done to him. But Bobby and Dean want retribution and assume Castiel does, too.
Castiel nods. He loves Bobby. He'll let the old man think his news will make Castiel feel better.
"We got Chuck Shurley going after that bastard-" (Dean and Bobby have a million epithets for Frederick) "-for everything he could be conceivably charged for. No pleas, no mercy. That monster's gonna fry."
Dean glows. "That's great!"
"Nothing he did was a capital offense here," Castiel points out. It wasn't a complaint, just an observation, but Dean and Bobby look consolingly at Castiel. Bobby puts his hand on Castiel's. Castiel winces, but Bobby doesn't notice.
"Hey, son," he says in his soft voice, "Gonna make sure he'll get the worst we can give him. And he'll sure as hell never hurt you again."
Staring at Bobby's hand, Castiel thinks that Frederick will be hurting him every day for the rest of his life. But he looks up at Bobby and smiles with what passes for genuine gratitude.