Good point about the randomness of Voldemort's methods. That bit with the diary in CoS really doesn't jive too well with the rest of what we know about Horcruxes. It seems strange that that Horcrux tried to take on a corporeal form by itself, like it had a will of its own, while the active bit of Voldemort's soul which had recently fled Quirrell's body was waiting around for another buddy to help him come back. Maybe it can be contributed to the fact that the diary has the largest piece of Voldemort's soul in it. Maybe that's what Horcruxes are *supposed* to do in order to give the person a second chance at life, but Voldemort's other Horcruxes can't quite manage it beacuse they're smaller bits of soul and the magic isn't really intended for anything less than half of one's soul. Hmm.