These are all based on an AU I came up with.
It's strange, I'll admit. Kind of a Crystal Gems story, with plumber aliens living with Ben, some aliens having similar stories to gems in Steven Universe (Four Arms grew up on Earth similar to how Amethyst did, Chromastone spent a lot of his life trapped in a mirror like Lapis, etc etc). The aliens (who aren't options in the watch) do have parents. Quickest explanation of that being they were formed from a very successful experiment of Azmuth's to see if life forms could be created through redone/reworked DNA samples, ecetera, ecetera. Since there are only two canon DNA sample-producers in Ben 10, the parents of the aliens are fanmade. (This doesn't go for Chromastone and Ghostfreak, although Ghostfreak's caretaker soon switched to a less evil person.)
Just a HUGE heads up, cause apparently this is uncommon (although I'm not surprised I'm mostly alone) in this fandom: THERE ARE A LOT OF GAY SHIPS IN THIS.
And if you like lemon or whatever...you won't be happy. I'm not a fan of writing or reading that. Fluff I'm always up for. But nothing that's majorly inappropriate.