I am always wrong said:
This seems pretty accurate to me with one caveat, which is how Ethan seemingly didn't put up a fight. He must have been asleep and attacked while asleep. But how would he be asleep and not up fighting for his and Xana's life after Xana said "there's someone here" and was crying presumably after being wounded? Or if he was killed first, how was he killed while Xana was awake without her losing her **** and screaming at the top of her lungs? I wonder if she was in the bathroom right next to the room while he was killed, heard some commotion, came out to tell him someone was there, but found him already dead, and then she was killed too. I never participate in this kind of morbid speculation and am not a true crime fan at all, but this case is really bizarre and intrigues the hell out of me.
My guess is, Xana said someone is here relatively quietly, she was not yelling it or screaming it. The roommate could hear it, because she's awake and on the same floor with Xana and Ethan. Let's face it, that house had people coming and going all the time, and it could have been a one-night boyfriend of Kaylee or Madison slipping out after a short sleep-over. By the time Xana realized it was a real threat, she was already being attacked and stabbed. Ethan unfortunately did not awaken by the "someone is here" comment, as we keep in mind he is sleeping while Xana is ordering food, messing with TikTok, etc (she's already making noise). A soft comment like that, while curious about what is going on, is done in a manner to not wake your friends in the house. I think the perp was scared and Killed Xana pretty quickly, and jumped on Ethan before he had a chance to move or know what was going on. It also explains the crying noises heard, if he has stabbed Xana but not completely killed her, she would be crying while he is killing Ethan, before returning to Xana.