The worst times were when Lucifer wore Sam’s face.
Logically speaking it was more apt for him to appear like Sam, Sam was his true vessel, and therefore Sam’s was his true face. But still every time the Devil’s face twisted from Nick’s to Sam’s Castiel felt his throat go dry. Perhaps it was because this ‘hallucination’ came from Sam’s head, or because Castiel knew Lucifer knew Sam so perfectly, but when he pretended to be Sam the act was flawless. The way he moved his hands, the small frown of concern, and the tired sad voice that had always cut so deeply, it was so convincing it was nearly impossible not to believe.
It was strange, to start with Lucifer had tried being Dean, but he had played it too brash, too loud, too larger than life he’d made Dean seem like some empty two dimensional hero and it made it so much easier to tolerate the devil’s games when they were so blatantly transparent.
He didn’t torment Castiel with Sam very often, he saved it waiting for the darkest and quietest nights, and then he’d sit, so very timidly on the edge of Castiel’s bed, Sam’s broad shoulders hunched as if he was trying to make himself smaller. Listing the horrors of the Cage in the most minute detail, every slice and tear, pointing out that if only Castiel had not failed to bring him back right he would have been spared, if only he hadn’t broken down the wall he wouldn’t have these agonising crystal clear memories haunting him. Sometimes he crowded in closer, leaning over Castiel his shoulders bumping against Castiel’s and it was impossible not to breath in Sam’s scent and here his familiar deep and steady breath, as he told Castiel how much it hurt and how much Castiel had failed him, made him suffer and let him be tormented by his own mind and the only reason he’d saved him now was to feed his own self indulgent guilt as if suffering now would somehow burn away his unforgiveable sins.
Castiel always wanted to argue back, to try to explain, or even just comfort this broken miserable Sam who wasn’t Sam, wasn’t even his fallen brother just some strange monstrous aberration in his mind. But he stopped himself, every single time he pushed down the desire to reach out.
Because Sam had told him, the real Sam he was almost certain at least that it had been the real Sam, he couldn’t engage it he had to stop it getting stronger and the only way was to not let it take more of a stranglehold than it already had. It was just before Sam and Dean had left, Dean had gone, sorting out paperwork and technicalities, but Sam had stayed in the room with Castiel, Lucifer playing with some kind of noisy light up yo-yo behind him. Sam had knelt down in front of Castiel so their faces were level though Castiel had been unable to tear his eyes away from Lucifer until Sam had gently caught hold of his jaw and tugged his head round so they were eye to eye. One of his hands a heavy but comforting weight on Castiel’s knee as the other one gently held his jaw keeping their gazed locked. As Sam, still with the scruffy messy beard and still looking exhausted, tried to tell Castiel how to deal with what he had shifted into his mind. It was garbled and full of apology, Sam tripped over his own words but he kept repeating, over and over to not talk to it no matter what it said.
Sam tried to coax Castiel to promise to him he’d not interact with Lucifer and told him he knew Castiel had the strength to hold back an d had faith that he would, he’d even got almost stern calling him ‘Castiel’ but pronouncing it in that oddly stressed way that Castiel had always felt strangely fond of, he wasn’t quite sure why. He’d managed to nod his head minutely Sam only able to perceive it because his hand had remained on Castiel’s chin the whole time.
So he didn’t answer back or beg forgiveness or try to reason with the vision of Sam that whispered to him in the night, or when it looked like his fallen brother with his sharp vicious humour and appeals for sympathy. He’d promised Sam he’d not reach out to it, as much as it may hurt him and shake him and taunt and torture him, Sam had told him he had faith in him. And whilst it was just about all he could stand to hold his mind together enough to follow a coherent thought he managed to hang on to that and that perhaps he could at least keep his promise to the one person who still seemed to see him as an angel.