If the first season of Scream Queens is anything to go by, then there's a good chance that Season 2's killer is a character audiences have already met. Hester was introduced early on and lurked creepily in the background before she was revealed as the mastermind of the Red Devil murders, so the Green Meanie is likely someone from the main cast. It's doubly possible that the killer is one of the newly introduced characters because audiences know the least about them – and they're already super suspicious. Setting off alarm bells right from the beginning is young doctor Cassidy Cascade, but is Cassidy the Green Meanie on Scream Queens?
There's no denying Cassidy is creepy. Though he introduces himself by claiming to be "the female Viagra," he hasn't exactly lived up to the claims. Cassidy has a deadpan affect that rivals Chanel #3's and he's unperturbed by every crazy thing he comes up against, but he's also hinted at having a dark side. His body is ice cold and he's prone to random, melancholic comments about the nihilistic emptiness of the world, so he's definitely got secrets that go beyond what his introduction implied. But does that mean that he could be the killer? The audience doesn't really know anything about Cassidy's past, so it's definitely a possibility.
Some have speculated that Cassidy is a vampire or Frankenstein-esque creature because of his chilly body temperature, and that does seem all but confirmed. In the promo for Episode 3, he tells Chanel #3 that he's dead, so unless he's speaking metaphorically he's either a supernatural creature or a medical marvel. There definitely seems to be something supernatural about the Green Meanie, too, considering the swampy origin story that started off the season. Perhaps swamp monsters are ice cold, too?
Cassidy's motives for undertaking the murders could be explained with just a little more information about his backstory. The origin story that saw a man murdered on hospital grounds and dumped in the swamp also revealed that the murdered man had a son on the way: a son who was born in 1985. That would make the son thirty-one now and a little too old for twenty-four year old actor Taylor Lautner, but he could easily be playing older than he is. If Cassidy is the man's son, then he has every reason to seek revenge on the hospital where his father died.
One downside to this theory is that when Dean Munsch was about to unmask the killer, Cassidy was one of the people who walked in on her. He was also on a date with Chanel #3 when the Green Meanie attacked Chanel #5. There's no way he could be in two places at once, so that would rule him out as the killer – or just mean the killer has a team of people working for them, much like Season 1's Red Devil.
There's one thing that's true about Scream Queens and that's that anything is possible, no matter how ridiculous it might seem.