Probably killed on the spot, unless the Headmistress -- well. Nothing good would have come of it.

Who would you have sent instead? Really, anyone caught spying on Bellatrix would have been in deep trouble. I'd have gone too, though, if Hydra had asked me. Not because I'm a Gryffindor, just because I wouldn't have thought about how dangerous it was until it was too late to back out.