My character Xefjord Kiromeda borrows his back story from when I roleplayed with him on Gilgamesh. But with a few critical differences in his history. On Gilgamesh, his sister died when he was young as well as his mother. This ultimately is where the Balmung and Gilgamesh timelines split, as in the Balmung timeline his sister and mother are never assasinated and his younger sister shelters him and bears the responsibility of being the heir of the company so Xefjord does not have to. Xefjord ends up becoming very reclusive and poor at socialization when he has his sister to do everything for him. His timeline on Gilgamesh was overall more scarred, and tragic from the stress of his sisters death. His father goes crazy and has experiments done on Xefjord as a child to ensure that he will survive and can continue the company. And Xefjord is forced to become very charismatic and try to deal with being the heir to the company. But in the end for both timelines Xefjord attains a thirst for knowledge which can not be quenched so he steals information from Garlemald and runs. In the Gilgamesh timeline he is alone in Limsa. Constantly living under the stress of Garlemald trying to assassinate him. In the Balmung timeline he is adopted into a group who protects him. Although the stress took a greater toll on the more sheltered Xefjord of the Balmung timeline. So I am not really theorizing when it comes to alternate histories for my character. I have played two histories for him and it is very interesting to see how he differs and is similar to his old iteration on Gilgamesh :3
