Bill Cipher is alive!!! (dun...dun...duuuuun!!!!!)
At the season 2 finale, Cipher is tricked into being erased along with Stan's memory.
it worked and everyone was saved but Stan forgot his memory.
after going through Mabel's scrapbook, he regained his memory... but wasn't that a bit too easy???
Turns out Bill hid deep inside of Stan's memory and is waiting for the right moment to escape.(according to my story) that's why Stan was able to regain his memory so quickly.
he is trapped inside Stan's mind.
He's patiently waiting for the tools he needs to escape to come to him...
Think about it. how was Stan able to recover his memories so quickly when Mcguket didn't remember his even after he saw the recording of his memory.
Stan and Ford swap clothes and Bill falls for it. 'Ford' agrees to let Bill into his mind. Bill enters the mind-scape. Stan reveals the plan after locking Bill in a room with him. In the real world, the true Ford gets a memory wipe gun and erases Stan's memory along with Bill.