Harry Potter: I'm a Reckless, Arrogant Lioness

I want to create a typical Gryffindor who is reckless, arrogant, and ignorant. The protagonist will only act sensible and self-aware in very rare situations. At times she's adorable, at times detestable, at times admirable, and at times hateful. She is a courageous Gryffindor.

Using her own intelligence, she rescues Sirius Black and successfully becomes Harry Potter's godmother. Because of her own foolishness, she misunderstands and despises Severus Snape. When the whole truth comes to light, she and Sirius can't stop blaming themselves.