Kait doesn’t get mad, just embarrassed. How would you react if someone else thought you had a thing going with someone else? Pretty sure Sam did something like knocking Baird with her elbow when he says that, though.
And I personally don’t want a Kait/JD thing. Not just because I don’t see it happening due to character conflicts and that I have no reason to believe it ever properly developed between when she got to know Del and JD and the end of Act 1 in Gears 5, and because I don’t see how TC would pull it off and not make it a horrendously cringy and exaggerated romance drama that just breaks apart very quickly. I could have seen her and Del happening but since the “choice” happened, I’ve just dropped even trying to predict any relations beyond friendship forming between the characters nearly completely when TC is clearly willing to kill off characters willy nilly when they could still be used for something else instead of a nonsensical death(cough Lizzie cough). Except for maybe Kait, Clayton and Marcus.
I really wanted them to build on the Kait/Marcus relationship more though, since it kinda seems like a pseudo father-daughter thing going on between them, with how he has started caring for her. But he was absent for 60-80% of the Campaign when we did play as Kait, so… that didn’t happen either.
