Suggest me a book exploring brother/sister relationship

Hi! I’m looking for a well-written book that explores the relationship between a brother and a sister (preferably little brother & big sister, but other recommandations are welcome as well).

Ideally, I’d like a book that goes a little beyond the cliché of “two enemies/antagonists siblings”, which I feel I’ve already seen a thousand times, and offers a more complex exploration of this family relationship. Thanks 🙂

by Misomyx