Uh...I just have a random thought..what if Crookshanks was Potter's cat? James and Lily Potter's! remember the letter Harry found at Black house? It said that Harry nearly killed that cat and...while reading that I wondered what happen to that cat? Where it goes?
Then remembered Crookshanks, he helped Sirius in POA and how on Merlin's name he knew him in his Animagus form? Maybe he remembered him from visit at James and Lily potter house and Sirius played with him in his Animagus form and..and..why he hated Peter Pettigrew so much somehow he knew that he betrayed his previous Masters
