Hermione’s Healer profession pushed her to try things she had never been too passionate about, such as potion-making for healing, and she would go down to the dungeons several times a week to make new batches of the most necessary potions. That’s how Snape and she got closer – it wasn’t a friendship per se, but after she saved him when he got bit by Nagini, Snape stopped bullying her, started teaching her the subtle art of potion-making, and even sometimes praised her quick learning abilities.