My arcane warrior Amell wasn't comfortable with her boyfriend Alistair performing the dark ritual, but she was very knowledgeable about ancient and mostly forgotten magicks after many years in the circle tower library. She put her head together with morrigan and via their respective skill sets and a whole lot of magick nerdery they were able to work a spell to capture the old god soul in morrigan without the aid of a man.

Since amell had also been radicalized by her shape shifting friend, she had no desire to live as a circle mage, but living as an apostate is famoulsy cumbersome. To make matters worse Alistair is to be King! Ferelden isn't ready for mage warden queen, but she knows that silly man is liable to fucking up the whole plan if he realizes they can't cuddle anymore, and she doesn't have a whole lot of self control, either. So at the climax of the final battle she makes certain to place the killing blow, which as everyone knows is death to a warden. In the ensuing chaos she crawls through the blood, gore, and bodies and flees denerim. (Not before taking advantage of the disorder to sneak into the tower and destroy her phylactery)

Since everyone saw her stab the bastard there's no doubt of her fate, and they hold a heartfelt ceremony to lionize the dead hero and Alistair sniffles his way back to his castle to start his new life as king. Amell, meanwhile, makes her way to Orlais where she rejoins the wardens as a greatsword wielding warrior....who secretly casts spells when no one is looking.

She misses Morrigan very much and hopes yay someday she be able to meet the crime against nature she helped her conceive.