Complex sentence: Alienated from her father, Commissioner Gordon, due to the unsolved murder of her mother, she becomes a thrill-seeking vigilante with her boyfriend, a circus acrobat named Richard Greystark, who goes by the alias Dick Grayson.
Split into simpler sentences: Alienated from her father, Commissioner Gordon, due to the unsolved murder of her mother. She becomes a thrill-seeking vigilante with her boyfriend, a circus acrobat named Richard Greystark, who used the alias Dick Grayson.