'Give me five minutes,' Castiel repeats, and with a shrug Bobby Singer acquiesces.
The hybrid appears scared, but not unduly; Castiel knows that he is not physically intimidating, and after all his 'batteries', as Bobby said, are 'flat'. With his contempt for Bobby's threats, the creature has, he supposes, become complacent. He thinks that the humans and the worse-than-human angel have nothing but empty threats and bearable pain to give.
Castiel sets about changing that. He does not enjoy it, any more than he enjoys watching Crowley show off his new toys like a gleeful child, but it is necessary and there is too much at stake to be squeamish. He watches skin peel back beneath the blade of a knife and thinks of the people whose lives are at stake. This is necessary. He must not forget that.
There are parts of him that hear the hybrid's screams and recoil, revolted by his own actions, but he tamps down the nausea and files those feelings away as he generally does with inconvenient thoughts, to be ignored at present and examined more carefully later, or perhaps not at all; it is not significant. He does murmur an exasperated request that the creature cease its cries of agony, but unsurprisingly the screams continue, so Castiel is forced to block them out and continue his work.
He remembers asking Dean to interrogate Alastair, and what Dean said: you ask me to open that door and walk through? You will not like what walks back out.
But that was Dean, and Dean is intelligent enough, but his perspective is…limited. He doesn't know how to separate a person from their actions, himself or anyone else; he carries everything he has ever seen and said and done with him, pieces of his past trailing behind him like cobwebs, and Castiel knows that he tortures himself over it.
Castiel understands, too, that what you do is not as important as what you are; it is he, and not his actions, who has endured for six millennia. It is possible, if unlikely, that he can endure six thousand years more, and by that time he will still be the same person, but the fact that he once stood in a police interrogation room and curled screams from the throat of a monster will long since have become inconsequential.
'Tell me where she is,' he says, at intervals, because he believes that is what is generally done, although the hybrid knows perfectly well already why this is happening and how he can make it stop. The creature refuses to talk, at first, so Castiel sighs and reaches for a smaller knife. He has never done this before, but he has watched Crowley, who is always proud of his newest techniques and eager to display them to anyone available; he does not exclude Castiel and, albeit without Alastair's theatrics, Crowley is very good at what he does. Castiel calls to mind the appropriate memories and sets about carving them into the hybrid's weeping flesh, and, after two hundred and thirty-four distasteful seconds, he is rewarded with a name and a number: 25 Buckley Street.
He wonders whether he should apologise to the bloody mess of a creature in front of him, but there would be little purpose to that, so without preamble he cuts the hybrid's throat - will its soul be one of those he finds in Purgatory, he wonders? and looks around for something to wash his hands.
Castiel can see the wary surprise in Bobby Singer's eyes when he tells him the address - had he been expecting admiration, or gratitude? Foolish of him - and he turns away with a flicker of irritation, to clean away the blood that stains his skin.