Ludo was an excellent character that went from
Your basic weak, ineffective leader that orders his lackeys around
To a broken, insane survivalist who finally gets the power he's craved since his abusive childhood.
To a man desperately trying find redemption and inner peace while fighting his addiction to power.
To a loving brother who helps all his siblings escape their awful parents and live happily.
The only complaints I have about Ludo's arc is that it barely gets any screentime after Battle for Mewni and he never gets a chance to play a bigger part in the story past that point.