It's a lie. Of course. Not one Severus told willingly-- he thinks he doesn't feel so much because, most of the time, he doesn't. What he does feel is warped and uneven, emotions filtering in improperly and over-saturated when they manage to connect. He doesn't know what he's doing.

"So you can have more dirt on me?" like a guttered-out candle flame, he sounds flat again. Even more tired than before.

"The first thing that happened to me when I stepped out of the medbay for the first time was Black breaking half the bones in my face." Dully. Because he doesn't remember if he mentioned that to Charles before or if it's just something to be assumed; being hit is so ordinary to Severus that he forgets when it should be remarkable. "I should have killed him. I would have. I'd still be in the brig, or airlocked. I hesitated because he looks like his dead brother and for that one second, that one second I could have just done it, I choked."

The anger in him over the Marauders is a never-ending fire. The fact that Sirius has punctuated his entire experience here feels like acid in him, eating away at everything, all the time. He can't ever escape them and he wants so badly to, he wants them to hurt, and suffer, and it's not a desire he knows how to be rational about. His hate suffocates him.