I for real can’t think of any show that does the “was complacent in an oppressive situation, went through philosophical turmoil, ended up fighting against the oppressor” character arc better than DS9
Odo, a morally-questionable repeat collaborator, spending so much of the beginning of season 6 moping around with the founder, essentially navel-gazing as his friends are arrested and harassed and demoralized, until “Sacrifice of Angels” when he steps up against his own people to save the station
In the same episode, Quark (the guy who dispassionately began restocking kanar before Dukat even set foot on DS9 after the Federation pulled out; a consummate acceptor of the status quo) seeing his brother jailed and recognizing that sometimes it’s necessary to rock the boat, even if it means standing stock-still in shock after you shoot two Jem'Hadar guards to help your friends/valued customers
Damar, the good soldier passed around from the Cardassian Empire to the Dominion, unreservedly supporting whoever happens to be in control while privately battling his own self-hatred; eventually recognizing that power alone doesn’t make a leader, rather, the fortitude to pursue the common good does
Sisko isn’t wrong when he says that Deep Space 9 exists in shades of gray, and that’s a good thing. Because the world is mostly gray, there aren’t often clear and constant heroes and villains, and it’s refreshing to acknowledge (especially at this particular period in history) that someone who was once on the wrong side of the road can have a change of heart.