[ Werewolf attacks are the last remaining thing that can send Severus into a panic - he's not panicked now, but he's angry, fuming, worried for Darcy, and already exhausted and in pain. It takes him a minute to gather his thoughts so he can do something besides scream at her, which he knows won't help. He tells himself to give her credit for coming to him before and not after. ]

If you have to be prepared to knock him out, it means he has no idea if the wolf will or will not harm you. Transformations here may not be like transformations at home. He's correct in that he needs to be kept from running free, but it must be done safely. For him and for everyone else.

Just locking a door won't do it. And you must not be in the same space with him, under any circumstances. It doesn't matter how safe it seems. It is not safe. No-one, not even with a perfectly clean history, can ever assure safety with a werewolf.