After the death of Friga Shatter-Shield at the hands of the Butcher of Windhelm (Blood on the Ice), she got intimately involved with Alain Dufont. She didn't know that he was a bandit who was used her to get close to Clan Shatter-Shield and rob them. When he did though, he took Aegisbane. Clan Shatter-Shield blamed Muiri and forced her out of Windhelm. She had to flee and eventually made her way to Markarth.
She is rumored to have performed the Black Sacrament.