Helloo!! Im another player but I still wanted to share my opinion although just to be safe:
spoiler :
ı think İsaac does care about MC. ıts just that his ''caring'' is more twisted and selfish than a caring you would expect in healthy relationship. İsaac does listen to you (maybe not everytime but he does) I think Isaac is just clueless about what he even wants himself. well he know he wants MC but he is kind of lacking details. But then Isaac is not purely innocent character either. while he adores MC there is a reason behind that too. regardless of his reasons and why he acts obsessed, Isaac doesnt use the MC or mostly likely he knows better than that.
These are my thoughts ofc ^^ ı think my overall summary is: Isaac does care about MC but lets say that the core of those emotions are bit more complex than to call it innocent and pure love