More than one rat
After the incident involving the Golden Trio, Scabbers, Peter Pettigrew, Sirius Black, Remus Lupin and Severus Snape, Crookshanks isn't entirely convinced the rat that was Peter Pettigrew wasn't Scabbers.
Crookshanks protested, "I saw you change into him!"
Scabbers said, "That wasn't me, it was a different rat."
Crookshanks asked with a frown, "There was more than one rat?"
Scabbers replied, "Yes, I've been here all night. The rat who turned into Peter Pettigrew wasn't me, he had a toe missing."
Crookshanks asked, "How can I trust you?"
Scabbers muttered, "We've known each other for almost a year now. If you can't trust me over a traitor, then there's absolutely nothing I can do about it."
Crookshanks gasped. "Oh, Scab, it is you!"
He pulled him into a hug.
Scabbers whispered, "Thank you for believing me, Crook."