The most interesting part with Leda for me, is that for all of the murder she does, she doesnt seem to enjoy it in any way. When she fights Ansbach, the Hornsent, Thiollier or you, she always seems to express some form of regret at having to kill you. Of course, she doesnt actually have to kill anyone, she is just very quick to use murder as a solution, but it doesnt seem to stem from a desire to hurt others, it feels like she genuinely believes this is the only way forward.
She says she is mistrustful of others, and while that convo is kinda funny, it really does feel like she has lost all trust in mankind. In the dialogue about Hornsent's crusade, while most people remember the "they were never saints" part, I mostly remember "Man is by nature a creature of conquest". It really does speak to how she views people, and it seems like she believes Miquella's forced age of compassion is the only way to change things for the better, that without his control, everyone would just constantly be at each other's throats. It almost makes me wonder about the needle kights. Did she kill them for the same reason ? Were they actually disloyal to Miquella ? Was there already infighting before she came along ? Whatever the case, Leda is now utterly convinced of Miquella's cause, and is ready to do anything to bring him to power.
It's a very interesting dynamic with Miquella, who is always portrayed as a very hopeful figure, always trying to create a kind and compassionate world, while Leda is a very pessimistic one. She seems to almost embody his "through whatever means necessary" philosophy. Had Miquella succeeded, i could almost see her taking on a role similar to the one Messmer took for Marika, an enforcer, someone who does the dirty jobs so their god can keep their hands clean. Hell, she's almost started to do it by herself, Miquella wouldn't even need to ask her.