Arthur's Warrior

When the Knights and Merlin are captured by Morgana, a person from Merlin's past comes to their aid. The Women who saves them is none other than Merlin's older sister. Elie is the leader of what seems to be a small group of travelling mercenary's. She was cast out by their mother for a reason that Merlin remains unaware of. In the time she had been away from her younger brother she became one of the best sword fighters in all five kingdoms. Her archery skills are above par and she is beyond beautiful. Elie seems to be on a different level than all the Knights and any women they have meet.
But she has a secret, one that could end up causing Camelot to fall. What happens when Arthur fall's in love with her? Will she admit her feelings for him? Or will Morgana find out her secret and tear everything apart?