All we know so far is that she once fought a wolverine. However, future episodes may reveal what she actually looked like and her fate prior to the series (whether she died, disappeared or simply filed for a divorce and is still living in the country). Perhaps she may be part of the reason why the Greens moved to the city?
- "Mama Bird" implied she may still be alive, as Tilly wished for her to "come back".
* Confirmed. "Phoenix Rises" reveals she was in jail in the duration of Season 1. "Uncaged" also confirms she and Bill are divorced.
Tilly is on the autism spectrum.
She acts aloof, is bound for flights of fancy, and seems oblivious to the world around her. Her antisocial and distant behavior is typical of those on the spectrum.
- That's unlikely since Tilly doesn't display the traits of a person on the spectrum. It's more likely she just eccentric, even more so than her family.
Expect the fanfic crossovers any day.
That's right, Bill Green is in fact BILL CIPHER!
They have the same name, they're both yellow, and they each have only one of a specific body part (Cipher's one eye or Green's one index finger).
There will be an episode set in a courtroom.
And the Greens are the ones getting sued. As their reckless actions come back to bite them.