My initial thought was Matthew's, but Myeong Ji will probably try to rip it out of her chest.  Then Joo Ran popped into my head, but I have no real reason to think that.  Maybe because she's so good with the children.

 I've finally settled on Chan Seong. In the last few episodes I think they're going to clean house so to speak and  get back down the original pahbos and crazed killer. I'm thinking w/n in the next 2-3 episodes Mo Ne will succeed in killing Chan Seong  in a way that won't damage his heart, which will coincidentally be a match.  Maybe it'll also be our opportunity to find out why he hates Min Do Hyuk so much. I really never bought that it was because of Mo Ne.

i think it will be yang jin mo...feels like he will die protecting someone.  maybe he will get tested beforehand and then finds out he is a match and somehow will think that this is his chance to atone for what he did..something like that. Kinda on brand for the level of drama this show has

I just saw the actor's IG post and I think that your theory is true.. after seeing his post I thought that ep 14 is the season finale🥲

 professionalfangirl101:

i think it will be yang jin mo...feels like he will die protecting someone.  maybe he will get tested beforehand and then finds out he is a match and somehow will think that this is his chance to atone for what he did..something like that. Kinda on brand for the level of drama this show has

 professionalfangirl101:

i think it will be yang jin mo...feels like he will die protecting someone.  maybe he will get tested beforehand and then finds out he is a match and somehow will think that this is his chance to atone for what he did..something like that. Kinda on brand for the level of drama this show has

That thought came to mind, but I dismissed it because of Han Na. How many tragic things can happen to 1 kid?

edit: I just finished ep 13.  Looks like you were right!