Not helping or supporting either of two opposing sides.Edit
The Fallon are mutants known to have chose neither side of the fight, or to support both sides. Fallons come from both sides: Noire and Edria blood. It is a choice, not a birthright. As a Fallon it is difficult just as much as being either Noire or Edria, because you have both sides coming at you to join them. The perks of being a Fallon? It is less violent, since you truly aren’t enemies with either side, but it also means that as a Fallon if the worse comes there is a chance neither side will stick up for you.