Throughout the Harry Potter story, Professor Snape carries a heartbreaking secret - something revealed in the character's very last line. Snape's Patronus was a doe, the same as Lily Potter's.

According to Wizarding World, a Patronus is generated through ... to show off the students he was most proud of. The professor questioned Snape's loyalty, especially after he killed Dumbledore ...

There are many instances in the series where it is Severus Snape himself who stands out as the best character.