All of it
As an autistic person who has trouble understanding social cues and tones I would be terrified to be bill’s friend 
He'd be hell even for neurotypicals to decipher. No matter how he's feeling, any time you look at him he's like,
Imagine you've lived your whole life riding by on the ability to effortlessly guess how everyone's feeling based on their facial expression. Then you meet a guy who's a sentient 👁️ emoji. But the face never changes. What do you do with that. What the fuck do you do with that. He's just,
Interpret his mood wrong and you die.
Edit: you don't get to interact with this post unless you understand the joke isn't "he's autism-friendly because he doesn't expect you to guess his mood from ambiguous signals like facial expressions" but rather "he's EVEN WORSE than normal people because he DOES expects you to guess his mood but he gives you ZERO SIGNALS TO WORK WITH." What about "interpret his mood wrong and you die" makes you think he's not making unreasonable demands. This is the opposite of a reassuring "your blorbo would understand and accommodate you" post.
Better late than never. Happy Valentine's Day!
Him
this right here is the bitch tree
it’s called the bitch tree because the bitch lives in there
ermm i made a lot of mood boards recently cuz they're fun so I'm gonna post some of em here :> heres one i made of Bill
Hmmmm Bill Cipher
Bill Cipher from Gravity Falls is left handed