"The soul thing seems to be fairly unique to the vampires from Spike's reality," Jack nods. "We've got - or have had - quite a variety here over the months and I don't think I've heard of any others not having souls." A quick grin. "Which is good, really, because we'd really be in a fix if you were all as much trouble as he was!"
And yeah, not getting into Tyki's unique problems. He latches onto Zero's slight change of subject instead.
"There have been quite a few who seem to have returned without their memories, yeah. None that I'm particularly close to, but for example there's a friend of mine, the Doctor, who's turned up from a number of different points along his timeline while I've been here, and never seems to remember being here before. Hard to say if each one is the same man or one from a slightly different universe."