Considering they are sentient beings they are basically Skywalker family/property, is it really so far fetched they would accompany Leia? Like, they can’t think for themselves and as much as Vader loved the thrill of being right in the center of the action so did r2. 3p0 just wants to be loved.
Have you watched the first season? It’s literally just a bit Mullaney made real. It doesn’t have to go long because the bit was done comolete episode 1. Every episode after is a bonus.