Sometimes you can't beat a good bastard in a story, someone who will do underhanded tactics to win, kick a defeated opponent when they are down or is always about the reward after they complete a quest/job.
Been reading The Greatest Estate Developer and it's your standard Isekai tale, guy wakes up in the body of a lords eldest son he read a fictional story about and knows they are in massive debt, all die to be the catalyst for the knight that serves them who's the MC. So he uses his architectural knowledge to change their fortunes but does it in the most bastard way.
He'll bitch slap an entire college full of stuck up nobles because he can get away with it, kurbstomp his opponent after he wins a duel to then trick him into exile, force a water contract on a rival noble that essentially binds his future generations to pay him extortionate fees and much more. This series jusy passed 100 episodes and has some of the best faces I've seen from a series.
So whether it's Leon from MobuSeka or Amos from The Expanse, who's your favourite fictional bastards?
Perturabo. Made nine-tenths of his legion kill the other tenth with their bare hands. Created the Iron Cage that broke the Imperial Fists. His sons are some of the most sick and twisted people in the Galaxy (Honsou is the primary example).
Even as someone who leans heavily toward the Loyalist, Peter Turbo is someone I actually like and respect (even as an Imperial Fist main). It is basically only him and Angron, and then most of the Loyalist. Every other Chaos Primarch I would gladly gun down with a smile on my face.