Medusa - Ban X Reader

The Seven Deadly Sins, only having 6 within their numbers so far, are venturing across the land, looking for the seventh, and final sin. But what they don't realize, is that a girl, looking around the same age as Elizabeth had been following them. She holds a deadly secret within her left eye, as well as a troubling past. As she becomes friends with the group, she finds herself growing closer to the Fox Sin, but will she be able to trust him after her secrets out?