But there is plenty of evidence that Snape was quite happy to get people expelled including Harry, in particular, and when he was at school, Remus Lupin. There is evidence in SWM, itself, that Snape was onto Lupin's werewolfism by SWM, that the marauders were actually discussing the DADA paper's werewolf question only minutes prior to Snape's examining that DADA paper so intently, that Dumbledore asked Snape to keep Lupin's lycanthropy secret, because in yet another attempt of Snape's to spy on Lupin that Black told him how to get past the Whomping Willow, which was as much a betrayal of Lupin as it might have caused injury to Snape, and might be the real reason why later on, Lupin was out of the picture when it came to being secretkeeper.