Question: Who was an enemy of the fictional character worked on by Esad T. Ribic that was the adoptive brother of Thor?
Sentence (from "Sif (comics)"): She has also battled alongside Balder, who has developed an unrequited attraction to her, as she never shows affection for anyone but Thor and certain individuals who have proved worthy to wield his hammer, Mjolnir, such as the noble alien warrior Beta Ray Bill and the mortal Eric Masterson.
Relevant evidence: No