Bound by the same scar-
The two main characters were both raised together in an orphanage.l Their treatment was terrible if one were to be kind. That is just the backround that will shared knowledge and nothing that we would role play.
It would begin when they both decide to run away from it. Once free of their care takers they both begin acting out every and all their fantasies with victims they lure away from others and taken to a hotel room the two live out of. (He may be a computer genius and hacks computers to steal identities and monetary funds. They are forced to live off of the grid so they rent this motel which is livable but far from what they could have paid if they wished. However such extravagant indulgences once satisfied tend to reproduce like rabbits which would leave them looking very conspicuous. Enough so that some busy body could look into who they are and what they did to earn all that money when they were obviously too young to even take a legal drink.
Perhaps she was in the orphanage before he arrived and she befriended him and together they realized that they shared many ideas and possessed attitudes which were so similar. He may be easily influenced by her and she used the prospect of losing their virginity together to manipulate him into doing something to her room mate. What? We can discuss.
Both may have felt that they must simply be evil and so they tried to hide it as best they could. When free to pursue their pleasures they realized that they should have been reveling in their unique outlook as opposed to keeping it hidden so far down that neither of them realized how innocent their original ideas were compared to their more advanced plans.
Soon he may realize that she gets sexually charged by dares he gave her which she never thought she would even consider until they both got high one night and together they shared their victim.
I don't have many offs but there are some limits.
No chars under 17
No baby play
If there are others I'll let you know but that is the majority of it.
Thanks for taking the time to read.