You know what would be the plot twist of the century that will probably never happen. The identity of Z, the one who's researching Ranboo, is none other than Alyssa.
Imagine it tho. Alyssa, in canon, left the SMP to avoid the rising conflict between L'Manberg and The Greater Dream SMP, but she also left for schooling. Instead of going to school to work with animals, she goes for behavioral psychology. While she's there, she spots an enderwalking kid who looked no more than Tommy's age, and she decides to investigate. He's slightly hostile, but Alyssa can tell that he's half-enderman, so she avoids eye contact. Then he starts to leave. And she follows. She documents what she's discovering; Alyssa is a friend to Enderwalk!Ranboo. She stays out of normal Ranboo's sight though, scared that he might be hostile. So she keeps following, until he leads her back to the SMP. She follows anyway, keeping an eye on Ranboo while staying away from everyone else, seeing New L'Manberg that set off quiet a few warning flags. Wilbur is a ghost. Tommy is now exiled. Alyssa just watches, writing things down. But now she's somewhere new, with a lot more people. So she marks herself as Z, a letter that wouldn't be able to link to anyone, not even her if she was found. She watches Ranboo blow up the community house, and watches New L'Manberg be bombed. She saw the Hell Tommy went through in exile, and she followed Ranboo when he left to live with Techno. She still meets with him, giving lessons and having him copy them down, to burn in his memory. But he loses his book, and Alyssa can't find it either. So she just watches, keeping up with her research, no longer speaking to Ranboo; just watching.
Then Wilbur comes back and befriends Ranboo. And it goes to Hell. Imagine that Ranboo is standing at a button that has a shit ton of TNT behind it. Alyssa sighs and just walks down there. "No. Stop it. Don't you dare or I swear to God I'll burn every memory book you have and put you in a permanet enderwalk state. Go back to Snowchester, go see your son, get your husband and for the love of God leave," she says. Ranboo just blinks at her, and slowly leaves, stunned.