Whether he or she is a pet or a wild magical creature, animals make many grand appearances in the Harry Potter series. Some of the first pets we grew to love was Harry's owl Hedwig, which was a birthday gift from Hagrid, and the rat Scabbers, which Ron had inherited as the family pet. As a fan who has just started to read the books, I was always curious about how Crookshanks came into Hermione's life. Upon reading Prisoner of Azkaban for the first time it was exciting to see why and how.
From the beginning of the book in The Leaky Cauldron chapter, one of the main reasons for Crookshanks is to add to the love / hate friendship of Hermione and Ron. While this is a worthy cause for the strengthening of their eventual relationship and the duo's chemistry, this is where my frustration with Crookshanks initially begins. The half-kneazle feline, for the most part, is really only used as a device to cause rifts between Hermione and Ron. It's not until we go further into the book that we come to understand something deeper is going on beyond Crookshanks' mysterious and vicious behavior.
But, at some point, there just seems to be too much Crookshanks.
In chapters 17 - 19, there is a plethora of revelations and information to take in at the Shrieking Shack. We have Professor Remus Lupin explaining the origin of the Maurader's Map, his werewolf transformations, and how/why the Shrieking Shack was created. Sirius Black has truths to be told about Potter's parents getting killed by Pettigrew's cowardice. And, we learn that Black befriended Crookshanks, when he was in his Animagus form, and used him as intel to know about Scabbers' (Peter Pettigrew) whereabouts.
The build-up of Crookshanks serving as a friend to Black is sold enough, however, in the actual revelation of Pettigrew's betrayal and Black's innocence, Crookshanks slows down the narrative. I didn't really care Crookshanks was apart of the story, and just wanted more of the suspense between Black and Pettigrew. Part of me had hoped Crookshanks was an Animagus of his own to make the character more rounded, which naturally never happens...
It seems funny enough that he's used too much for Hermione and Ron's relationship as the go-to quarrel maker, but when used for other means, I could really have cared less. At the end of Prisoner of Azkaban, we are left with a simple companion to Hermione, who we suspect will be the cause of more rifts with Ron and his new owl.