Sibel Gunthor was approached by government officials during an art exhibition, and asked to come in for questioning over suspected telepathic activity. She had always been a low-level telepath, but the crimes she had been accused of perpetrating were well beyond her. While the officials quickly realised she was not involved, Sibel volunteered to help track down the real culprit. The case was resolved with the assistance of Sibel and the German uberhuman team, Uber Force. Sibel was invited to join and she accepted, going on to become one of the most powerful members of the U-Force.

She is the third longest serving member of the team, and has managed to pursue a professional career as a sculptress as well. She is well known and respected among Germans. As U-Force has begun to turn its attention to the capture of Kinder der Zukunft, Sibel has proven that she is both powerful and slightly chaotic in her own right. Recently, she has lost her temper more and more easily. Although she has not been medically or psychologically tested, Sibel believes that after ten years of superheroics, her constant use of telepathy has unhinged her mind. She has not shared this concern with her team mates, but is worried that she may lose control.

Sibel is an artistic woman, who grew up in a very prestigious family. She never felt stress or expectation until she was drawn into the world of the U-Force, and it was in this new life that she felt truly useful and able to make a difference in the world. She is one of the most experienced members of the team, and has a level head when it comes to most uberhuman activities.

However, lately she has experienced mood swings and has lost her temper in violent displays. She is concerned about her lack of control, but is not confident enough to share these concerns.

"You can't hide your violent thoughts from me."

Immorta has telepathic and telekinetic abilities. She is able to communicate and control minds, curb an opponent's intelligence and reaction speed, create vivid hallucinations and intense psychic energy blasts. She is also able to manipulate the world around her with telekinesis, such as flying, forming force shields and bolts of telekinetic energy.

Immorta is a beautiful woman, with classic German features. Her hair is blonde and her eyes are turquoise. Her costume has been designed by a friend in the fashion industry, a curving turquoise and white design which is figure-hugging and also provides protection from most conventional weaponry.