Morally gray main characters

Hi guys! This is extremely specific because it's based on a dream I had today. I'm looking for book recs that focuses on villains. A morally gray mmc and his powerful ally, fmc (who is also a morally gray). She has a huge misunderstanding between them and leaves him. Misunderstanding is then solved and she comes back to him and loyal to him now 110%, she is like the main shield/protector on his team. It doesn't have to be romance but they have a good chemistry. Thank you! 🌸