Heck if I know why Bill’s so stinkin’ endearing. He’s a dangerous, crazy, menace that sounds like a salesman yelling through an electronic voice processor. And he seems to enjoy tormenting people. Normally, those are viable grounds for wanting to punch someone in the face, so a large part of his charm and intrigue probably comes from the fact that he keeps stuff interesting. Like that kid that sits at the back of the class and shoots spit wads at everyone. And the fact that the GF team obviously did their homework when tying traditional triangle symbolism (like fire, power, and change) into his character also amps up the intrigue. Idk, I’m a huge sucker for symbolism in media.
The closest thing I probably have to a headcanon about the Bill (and it’s probably more along the lines of an incredibly topical character interpretation) is that he’s really vain. I mean, he’s a shapeshifting terror that has absolutely no need for clothing or other adornments, yet his go-to form has a top hat and bow-tie. He could get away with just being a shape, but he goes the extra, ostentatious mile.
He totally thinks he’s pretty.
Gonna be lame and say that I don’t have too many theories, but I am speculating that Bill’s Wheel is a sort of interdimensional house-arrest bracelet and the people represented by the symbols on it are the key to freeing him from it. He’s powerful enough as it is, so you’d think that whatever he wants he could get by himself, yet it’s implied that he at least needs the help of Gideon, the Twins, and Soos (all people with symbols, Gideon unconfirmed) to accomplish some end down the road. This kinda makes me think that the Wheel is the limiting factor in this whole equation.
Ok, I’ve had my ramble. Gonna toss the ball back in your court and ask what YOUR theories and headcanons are.
Yes! And interdimentional house arrest bracelet! Like, maybe he can only enter people’s minds right now, or only act when summoned. And with the help of all these people, he could, you know, become a real menace! It would be sweet.