This work could have adult content. If you proceed you have agreed that you are willing to see such content.
Gwen is not sure if she and Merlin are sharing Arthur or Arthur and her are sharing Merlin or even if Merlin and Arthur are sharing her. She is just sure they are sharing something. [Arthur/Gwen/Merlin, with elements of Arthur/Gwen, Arthur/Merlin, Gwen/Merlin.]