In Lily's letter to Sirius, she mentions how Harry nearly killed the cat with the toy broom that Sirius got him. Well, what if that's the reason that Crookshanks has a squashed head and a flat face? <<< This makes perfect sense!
Honestly though he would've been a million times better off had he been raised by Minerva McGonagall. <<but he wouldn't have been as safe without the blood protection. Maybe he would have had to visit the Dursleys every year?