A young healer who claims to come from Volantis, one of the Free Cities. Maegyr is a family name shared by one of the leading members of the Old Blood of Volantis—descended directly from Valyria—who is a triarch. Her appearance does not fit the Old Blood look at all; more rightly she should look much more like Daenerys.
It is our understanding that this character was originally Jeyne, presumably intended to represent Jeyne Westerling, a young noblewoman of the Westerlands, even though she does not actually appear in A Clash of Kings. However, it appear the production changed their mind sometime after the casting of Oona Chaplin, as the character is now called Talisa instead and said to hail from Volantis. As such, it appears she is a brand-new character that does not appear in the books.