The thing that pissed me off with Kreacher (SPOILER)is that he is part of the whole reason that Sirius DIED! He's the reason then went to the Ministry of Magic. Hermoine told Harry that they needed to go into the fire to check (SPOILER)if Sirius was there to make sure it's not a trick, and if he wasn't there, they would go. Kreacher hurt Buckbeak due to Bellatrix's orders (remember how he left around Christmas?) (SPOILER)so that Sirius would stay in the attic, then he told Harry "Oh, Master is gone for many hours..." so that he'd leave. That whole thing was left out.