Harry Potter: The Worst Thing Every Order Of The Phoenix Member Did

Looking back on it, the book's depiction of James and Lily Potter's courtship is a bit difficult to navigate. Through the use of Legilimency, Harry is able to look back into the memories of adversarial teacher Professor Snape. It's here that he finds his mother Lily detesting his father in their 5th year of Hogwarts at age 15. 5 years later, and the two had made up, dated, married, and Harry had just been born with Voldemort hot on their tail following a prophecy made about his death.

Why did Lily feel so strongly about James? Well, as it turns out, James was a bit of a bully in school. Flanked by an encouraging Sirius, a resigned Remus, and a timid Peter, James took delight in tormenting Severus, an ambitious, conniving Slytherin. Both men were infatuated with Lily and became intense rivals, with Snape setting out to determine the lycanthropic origins of Remus Lupin, while James used jinxes to bully Snape just for fun.

Potter's treatment of Snape got so bad that Lily, his best friend and unrequieted love, claimed she'd rather date a giant squid than James. It's a startling realization to young Harry to that his father was not as idyllic as he had imagined, but had flaws and shortcomings, the same as anyone.