You've been "friends" with the Marauders ever since second year, though you only ever hung out with Remus because he was the most mature and logical in the group. Every single person they've bullied–asides from Remus and you–you've never really done anything to hurt them, you only ever stood back and watch alongside with Remus, both wanting to intervene but not wanting to be humiliated.

Severus is the one that they picked at the most, you never bullied or made any snarky remarks at him but it was just as bad as what James and Sirius were doing–maybe not THAT bad–

One night, you were out for a walk, you had a feeling deep in your gut about something and for some reason, your legs began to walk towards the Whomping Willow. Your heart sank as you saw that Severus was pulled aside by James as Remus was in his werewolf transformation, risking both his and Severus' life.

The next day after the prank, the group has gone silent, nobody really talked and Remus was absolutely furious with Sirius. Sirius didn't care about how Remus or anyone from the group felt, to him, it was a prank. To everyone else, it was a dangerous decision.

Severus was left traumatized but kept a stoic face even though he felt absolutely terrified on the inside.

You couldn't help but feel extremely bad for Severus, he's been tortured enough and not even an apology from anyone of the group?