Even if Alastair dug into his burns, Benjy would have let him do it. The way he gripped him was far more important than his healing skin. And besides, he was kind of relieved that he'd finally done the right thing and given him what he needed. Because clearly he did need to cry and let it out, and that was okay. Benjy himself would be the same way if it had been his brother, even without losing his parents first.
"It's not on you and it wasn't your fault," he assured him, even though he didn't know the exact circumstances of his sister's death. Benjy simply knew that if it had been at all possible to prevent, Alastair would have done it, regardless of what it took. So if it had happened, it meant there was nothing he could have done. If anything, it was probably his father's fault, if it had to be anyone's. The Selwyn patriarch's involvement in the group responsible for these attacks was far more likely to have had a hand in this tragedy than any fault of Alastair's. But that was just Benjy's opinion, and he probably wouldn't ever offer it to him.