Marti Södergren was a sorceress who specialized in healing as well as aphrodisiacs. She had fiery red hair, though it is revealed that she dyed it that color. She had a reputation as a seductress, and according to Philipa Eilhart, was a nymphomaniac.
She tried to save Hen Gedymdeith when his heart gave out after the reception on Thanedd Island, but she was too late. She is confused and shocked by the events of the Thanedd Coup, and she breaks into tears after failing to save Hen Gedymdeith and being hit across the face by her friend Sabrina Glevissig. It is in this state that Geralt finds her in a window alcove in Aretuza, at which point she shows him the shortest route to Garstang. Shortly afterwards, Geralt and Carduin bring back a wounded Dorregaray after he is shot with an arrow by the Scoia'tael, asking Marti if she can heal him. She uses healing spells to try and fix his punctured lung. As Geralt and Carduin leave, she stays behind with Dorregaray when she realizes that he cannot walk and that Carduin cannot teleport them due to the effects of the portal in Tor Lara.
She also took part in the Battle of Brenna, working under Rusty in his field hospital. Shortly after the victory Marti had a careless love affair with a Free Company officer, who treated their relationship too seriously and stabbed her to death out of jealousy when she got involved with a Temerian captain two weeks after the battle.