Blackfire is Starfire's evil older sister and one of the most wanted criminals in the galaxy. Her rivalry with Starfire is mirroring Brittany and Eleanor's rivalry in Alvin and the Chipmunks: Sister Act.
Learning to be a good sister
Teen Titans Go! comic book series
Blackfire is shown to be nothing like her sister, Starfire, being opposite of her. She knows more of Earth's customs and is not as naive, unlike her sister. She is shown to talk more like a normal teenage girl. She lacks eyelashes, Unlike Starfire. Blackfire seems to hate her sister, and will do anything to destroy her. Yet she has a change of heart (or has been believed to) in the end of the episode "Mr Butt".
She wears an outfit similar to her sister's, but with metal parts covering certain areas and it is a black coloration with pink and purple gems instead of green. Her hair is similar to Starfire's, but it is dark purple instead of reddish pink and shorter, reaching her waist instead of her ankles. She also has paler skin and just one eyelash on the side of each eye.
She appears to have the same abilities as Starfire, but stronger.
Blackfire is Starfire's older sister who hates her and has always bullied her. Despite this, due to Starfire's naive and sweet personality, she never got upset with Blackfire. Toward the end of the episode, Blackfire figured out that Starfire had always loved her and that she was being a big starbolt-shooting jerk.