I feel like Bill is one hundred percent the kind of person who would sneak a space cat back onboard the TARDIS.
Like, they go to some intergalactic space port on some super serious mission, only it’s a false alarm so they head off and the Doctor is talking away, right until they get back into the TARDIS, and then he’s interrupted by this small,
Meow!
Bill winces. Naturally, she denies she heard anything - says she doesn’t know what the Doctor’s on about.
Only it gets a bit difficult to hide whenthe thing slithers itself out of her coat and starts flitting around the console room.
Bill justifies herself by saying it’s cute. The Doctor doesn’t see how anything with that many eyes and fangs and feelers can be cute, but eventually he decides to let her keep it.
She calls the “cat” Peaches. It lives on the TARDIS and tears up all the seats. The Doctor would try to stop it, but every time he tries to get anywhere near it the thing starts hissing and spitting acid. He’s decided to just let it be.
