...I really love this book, okay?
RANT. You have been warned.
Some people might see Mercy from Braveage as a cliche because of her badassery and sexually liberated nature. However, there is one key difference between her and most tropey villain/anti-heroes:
Mercy Flora Hallows does not change. She does not become a better person. She does not grow kindness or even a new life outlook. The situations she finds herself in shift and change, but she is always the same horrible person that she was at the beginning of the story.
And yet, she is not completely cold. She's not a sociopath- that much is clear when Eldlo dies and Milo nags her until she admits that she's angry that her boss has left her with no job, almost no friends, and no security to her life. She's damaged beyond repair, but she's not something physiologically wrong with her. Unlike so many anti-heroes in stories like this, there is nothing really wrong with her, and yet she shows no signs of being reformed.
There are parts in the story that yes, it appears like she cares in some way or form for members of the "merry little band" ((hehehe....)), but, if this makes any sense, it's a very selfish caring. She sees them all as expendable dispensers of something she needs emotionally. If one of them were to die, she wouldn't be horribly upset, more annoyed with the inconvenience of finding someone else to fill their place.
She needs Endymion as a source of authority and something to strive for. Though it is still for her own purposes, she craves acceptance and admiration and Endymion is someone who doesn't give those things willingly. He's a challenge to her and though it bothers her that he doesn't seem interested, she needs that challenge.
She needs Tallys because she must feel superior to someone who does not accept her way of life. It's not some tragic "oh- she's a whore because she has no self-esteem" thing. It's that she honestly doesn't have the social skills to understand why people see her as amoral. And along comes Tallys, who judges her every breath, but is actually a quite pathetic figure herself.
She needs Milo because he fills the place of Eldlo and Rian in their absence from her life...and bed. She needs someone to own and manipulate, and with Eldlo being, well, dead, and Rian in a monogamous relationship, she needs someone else. She needs someone who basically just puts up with her shit- not necessarily loves her, just puts up with her- no matter what. They don't have a traditional romantic relationship, but that is because their understandings of normal relationships are skewed. Basically, Milo is the closest Mercy will ever get to a functional relationship, which is the reason she also hates him, sadly enough.
I'm not really going to try to hard to explain Axel since he's basically an extension of her control over the others, particularily Milo and Tallys.
And lastly, she needs Adiria because without her, Mercy would have nothing to do. Really, she needs direction. She can't just make her own way and decide what to do with herself, she needs a cause and whether it's working with or against her, the only cause she has now that she is no longer welcomed with the provosts is in relation to Adiria's struggles. This is the other way in which she replaces Eldlo in her life. She likes her freedom to do what she wants (thus the tension between her relationship with Eldlo and their jobs as provosts), but she needs a source of livelihood, just like anyone else. She requires something difficult and stimulating, but loose. She could never prostitute herself, because part of her fascination with sex is her ability to manipulate her lovers to please and think of only her. If she were asking a price, she would have to put someone else's needs before her own and that is something she would be incapable of doing. And so for most of her life, the provosts had offered her that freedom, just so long as she kept her small amount of control over Eldlo. Without him, she needs Adiria for her source of purpose.
She needs them all, not in a survival sense, but in a deeper, emotional way. She probably needs Adiria and Milo the most, as they offer a substitute for the homeostasis she had in her life before the start of the story. So she does care about them, but only so long as she feels like it would be inconvenient to replace them.
This is what sets her apart from characters like the mord sith in Legend of the Seeker. Even surrounded by the "good guys," she still doesn't develop moral sensibilities.
I really love this book okay. Shut up. I warned you.
I JUST HAVE A LOT OF FEELINGS OKAY