I dont think they slept together. If I remember it right someone who read the novel spilled that there is no incest happened between Roxanna and her sibs.
It's like Dion has an obsession towards Roxanna but it didn't cross the sexual territory. It is more of familial but kind of twisted.
He's just obsessed with her, he himself would probably freak out, if it went that far. She just decided to use his weird obsession to her advantage and all it takes is as much as just giving him a little bit of attention
Oh thank you so much everyone
Wait im confused. What's up with dion? Is he in love with roxanna? And that's how she been using him as her puppet? Wait does that mean she slept with him in exchange for using him or she is just leading him on?