I vote for villain's dog next. Not a person but actual dog.
Don’t forget villain’s father. Also, I think there is already a novel on a villain’s dog.
LOL
There is als a novel called The villain's butler or something-- can't remember the exact name though xd
There is an manga for isekai into a op fluffy dog, for a princess not a villain's though.
http://www.mangago.zone/read-manga/wanwan_monogatari_kanemochi_no_inu_n_shite_to_wa_itta_ga_fenrir_ni_shiro_to_wa_itte_nee/
Ummm could you link all that you’ve just said please? (=・ω・=)
do you guys have link? Lol
The butler Novel -> https://www.novelupdates.com/series/the-villainous-daughters-butler-i-raised-her-to-be-very-cute/
Idk if you wanted this but I shall link it for ya.
villain's maid, villain's savior, villain's mOTHER WHAT ELSE OMG
it's a nice pace though compared to just being the villainess themselves