Glad to have William/Billy backstory. Even more excited to learn where Tommy is, but I expect that will be the focus of a future show. I think we'll get just enough to be satisfied here.
I'm curious if there is a connection between Eddie sending Billy a black heart text, 🖤, and the list drawn up earlier in the season where Rio represented the black heart. Maybe the connection is just death, but maybe something else?
I definitely hope we get more backstory to William/Billy. I think the big question hanging over the series now besides Tommy is ...
spoiler
Why is Billy "evil"? It doesn't seem like killing Livia and Jen served any real purpose. I guess it's supposed to read as something he did accidentally in a burst of temper, but that's not much better. I get the sense that the show still wants the audience to like him or they wouldn't be spending time on introducing his sweet boyfriend. But even with Agatha guilting him about it, we didn't see much in the way of remorse. I think the show is too well-written to just have him be evil because he just is.
For what it's worth, I'm not at all convinced that Livia and Jen (or Alice, or even Sharon/Mrs. Hart) are or will stay dead, so maybe that's the redemption arc. Perhaps at the end of the road, when Billy finds what he's missing, it's not Tommy but the lost members of the coven.
Nice to get the payoff to the call-forward "A lot happened to me at 13, too."
I'm guessing there is something a little bit more to Billy that we still don't know, specifically as it relates to his spirit inhabiting the now dead William Kaplan.
First at the end of the episode Agatha mentions something about Billy breaking the rules in terms of him having a body.
We've actually seen this before in Multiverse of Madness when 616 Strange inhabits the body of dead Strange. Demons appear and terrorize Strange.
So a spirit entering a dead body breaks someone's rule. However Billy is clearly fine. In which case Billy, or someone on behalf of Billy, made a deal to keep Billy alive.
Now in this episode we saw Lilia put the sigil on William Kaplan, before knowing its purpose. If she has this power, it's possible others also have this power.
So someone, knowing it would payoff later, facilitates Billy Maximoff's spirit entering William Kaplan. In fact this same someone probably also ensured the accident happened the way it did.
So who is this someone? Well in Multiverse of Madness we see minor imps or demons. We also visit the throne of Wanda/Scarlett Witch, created by the demon Chthon, author of the Darkhold. But I suspect there is probably someone higher up in the demon tier list. Or maybe Chthon goes by multiple names. A name we've already heard once in this series. Someone Agatha is known to have made a deal with.
That's right, Mephisto.
So Mephisto saved Billy, knowing it would pay off later, likely to control Wanda. But also it could be an Ego the Planet situation where having Father/Son, or in this case Mother/Son makes everything more powerful.