User blog comment:Rose234/possible new female character in Merlin/@comment-4956800-20120730193430

Gwen's servant would be a Lady-in-Waiting. Now I'm quoting wikipedia:

"Historically, in Europe a lady-in-waiting was often a noblewoman from a family highly thought of in good society, but was of lower rank than the woman whom she attended. "

But following your logic that woman may very well be Gwaine's sister.