He doesn't like her that way according to spoilers. When they were children, they are close to each other (MCs brother and Dion too). However, ever since Dion killed the brother. He probably went insane and watching the MC look at him with so much anger satisfies him. Dion desired to be killed in her hands.
He doesn’t like her in that way he just has a sibling obsession like jeremy but his is a different reason in novel it’s more like a we both have been through same thing and backstory they both follow the commands of their father to survive which is why he killed her brother it is their dads order since her brother failed the test dion was ordered to kill him and he had to do that to survive
Wait someone pls explain, aren't Dion and the FL siblings or at least cousins, does he like her in that way?