One of them is a man. He's in his 40s, very worldly, brilliant, manipulative, deliberate, and sociopathic. He is intentionally malicious and cares about no one but himself. He tries to damage a character's relationships with other people on purpose, engages in gaslighting, lies, and forces people into situations where there are dependent on him so that he can demand they owe him. He is unhealthily obsessed with the character he is sleeping with and causes real harm in his attempts to forward his possessiveness and jealousy. He's smooth, sly, and passive-aggressive.
The other one is a woman. She's 24, very naive, guileless, terrible at lying. She made one very bad decision and found herself mixed up with bad people in an attempt to right it. She is by nature honest and has the best intentions, owns up to her mistakes, calls people on their bullshit, and won't engage in games of manipulation. Her mistakes are all made in the service of friends, and she will put herself in danger to help the people she cares about. She is supportive yet not enabling, sets good emotional boundaries, and listens to other people's problems until she thinks it's unhealthy and then tells them so. She's defiant, stubborn, and temperamental.
Guess which one of these characters readers loved and which one they hated.