(notice to snape stans, i dont hate him, but i'm not a fan of him btw! so pls don't interact with my blog if it bothers you to see some snape criticism now and then)
lily evans- his first friend/childhood friend & also his first crush, although never reciprocated. taught each other lots of stuff & studied together often. slowly became more and more distant as they got older, and political/moral views changed and developed
avery- one of his roommates. his second friend, first person (other than lily) to stand up for him. severus then began to look up to avery a lot and he became eager to impress him
mulciber- roommates, sort of became friends as he got closer to avery. i imagine mulciber being obsessed with proving himself to the 'cause' & getting severus to do the same
wilkes- roommates, also became friends as he got closer to avery. not as close to severus as avery or mulciber but still count as friends.
lucius malfoy- i think severus looked up to him a lot, and in the death eaters, lucius was kinda in charge of giving voldemort's orders to them & keeping an eye on them. but weren't friends till they were older
narcissa malfoy- became friends though draco. lucius asking severus to look after draco throughout school, and he does which obviously means narcissa is gonna like him. also i feel like they get each other, despite the plethora of differences between them
charity burbage- weren't friends during school, but became friends whilst they were both teachers. very different people, but i think charity would remind severus of lily a bit (in terms of personality) & he'd be clutching onto that