I would say romantically.
Harper does care about Adrian and wants him to be happy and get over his grief. When the party happened he seemed down because so many people showed up and he knew Adrian would get out of there. The second time he was more considerate and made sure only the Mindy? Showed up.
Then the teasing but he never oversteps while knowing more than he shows.
So I would say mutual crush on each other.
they kissed two times I think? The first time Harper kissed Adrian and Adrian just happened to kiss him at the same time , so both of them unknowingly went in for it at the same time. So I’m saying there’s a bit of romantic feelings on Harper’s side
So Harper is just ok with these kisses? I can't figure out if they're interested romantically in each other or if they're just friends who are physically attracted