i just read over his bio and i have a few possibilities if you're interested! i believe she and overheat were close for a while and she let her into her little bubble until jos turned 'good', which caused a rift in their friendship. she could either have him pegged for a mark because her loyalties no longer lie with her/their family, or we could have it so that they crossed paths at a fancy party one night and hit it off. maybe she was there with a client but spent most of the night talking to ethan and they entered some kind of mutually beneficial/extremely toxic friends with benefits situation. OR we can say that she pegged him for a mark, but he caught her mid heist and they duked it out and have been enemies ever since. I HAVE A LOT OF IDEAS but any/all of them are fine with me!