Working on a Doctor Who/Gravity Falls AU
Setup: When Ford and Stan were conceived their parents were in a hotel next to a planetarium, maybe on business for something their dad was doing. Little did they know that a scientist who worked there had been experimenting with time travel, and after a run in with the Doctor he opened up a time vortex that was originally created by some damage done to the TARDIS. It was only briefly, but it sent out enough energy to have a huge effect on the egg that would eventually become the twins.
Now I have to decide between these two base ideas
Possibility 1. Their mom was originally having a single baby. A fertilized egg from an alternate universe is placed in with her existing egg due to the rift. Stan and Ford’s genetic makeup is all but exactly the same because they're actually the same person, just from different universes. Despite what one would expect, Ford is the "original" and Stan is from the different universe.
Possibility 2. The split in the egg was directly caused by the malfunctioning TARDIS. When it splits the missing half of each is filled in by the time vortex, creating two almost identical beings that are neither human nor timelord. Each embryo has a bit of time magic stored in it and pieces of the TARDIS are literally written into their genetic code as they develop. They both know something is different about them but it's not until well into their adulthood that they actually see the true affects of their TARDIS DNA.
Idea: Ford had to regenerate several times when possessed by Bill and Bill always forced him to keep the same face. Whenever Ford regenerates he always keeps his six fingers as well, but that's his own choice
