I think we could protect Sarah, if it's Sarah. I'm less certain about Ptolemy, if that's who you want to keep safe. The better someone is with a wand, the harder it is to take them alive.

It's surely not Antonin Dol

Look, there's no guarantees, regardless. We do try to take care of our people and those they love, even when they're not terribly savory individuals, but we don't always succeed -- we weren't able to keep Lucius Malfoy out of Azkaban, last summer, for example, though at least Voldemort didn't kill him outright, and we got him out later.

It's entirely up to you whether you tell me. But if you don't tell me, I won't know who it is you want me to protect.

I don't think you lose anything telling me. Unless you think I'd try to use that person against you. Are you worried I'd do that?