I can see these two having met before canon and being friends or dating each other. They have a similar rocker style of dressing. Maybe they went to the same charity shop and found band tshirts and CDs. Also Luka has a tendency of supporting super shy anxious people like his sister, and Marc is anxious when he first appears. I can totally see them being exes who stay on good terms or who get back together later.
Listen, he is going off the few people in this world that Luka hates. In the view of an enemies-to-lovers girlie, I think that this makes the potential so good. Imagine this, they would probably be forced to collaborate at some point and the tension would be real. XY as the self-absorbed prick that he is wouldn’t realize that the tension and hate are there and would never keep his distance from our beloved Luka. And, Luka’s tension would keep building up and up, and I think that he would end up exploding. In this case, he can't punch him, so he just kisses him, hard. They start making out and this would change his view of the boy 180º degrees. He would look at him in a different light and try to impress him. Even as dumb as he is, he would see that Luka just wants him to be a better person. Luka would realize his efforts and fall for the boy too, as the cinnamon roll that he is. Could this be the plot of some fanfic for these two? Maybe. BUT the truth is that XY it’s just dumb and misguided by his dad, so Luka could be a good influence on him. Luka, being the softie that he is, would end up treating him better and try to understand him and see that he is just freaking dumb but has a good heart.
