Long after Bill Cipher had supposedly been put into the interdimensional prison, a new face shows up in gravity Falls {y/n}. A child who just lost their parents, and was left in the care of Stan and Ford Pines. They came with both good and bad news, Good news :Bill Cipher It's now completely gone because he had a living vessel that absorbed him Bad news:  they're the vessel, and theyll be living in town, Worse news: the Gleefuls got to her first, they only figured out that {y/n} was the vessel when they saw the tattoo. Bill wasn't fully absorbed until {y/n} was ten. They were a newborn when they became the vessel,growing up they assumed that bill was just an imaginary friend, and he was just playing with them when he taught them these spells.. in reality he was training {y/n}, in hindsight, They should've seen that because he prevented their death on multiple occasions.
{y/n} is a new Android the crew is transporting to Risa, a model of Android known as an "IPB" or Interstellar pleasure bot. They are made to relieve people of pent up stress in the most intimate way. Then they figure out that {y/n} is sentient like Data only after turning off factory settings, after which they act more like a human member of the crew, granted a quite flirty one who seems to know just what buttons to push which comes in very handy when the one and only Q shows up