>>102397402
>Sitting
Intimate setting, you are able to see more of Reimu, her expressions might be calm but welcoming to the dragon. Basically the vanilla option. The position also implies acceptance and a stronger connection between them, she is definitively welcoming and accept it.

>Standing
Powerplay by the monster, she is being used by his pleasure only so it can swing between rape and power to degeneracy and degradation. The position implies dominance making Reimu understand that the dragon is in control regardless if she is enjoying it or not. She is now the dragon's pet.