Sloth is the result of Ed and Al's failed human transmutation of their mother. She was severely deformed but somehow found her way to Dante. The elderly woman fed the homunculus the red stone until she took on the shape of a human. Although she has no soul, Sloth did retain a few memories of her life as Trisha Elric.

Once she became strong enough, Pride (the Fuhrer) manipulated some military records so that she may infiltrate the army as his secretary. She took on the alias of Juliet Douglas. As with all the homunculus, her goal was to get someone to create the philosopher's stone. Her ability to liquefy and shape shift made it easy for Sloth to eliminate anyone who may get in the way. It was Ed who was finally able to stop her.