Yonah is the original creator of Battle Angel, and a generic Bad Guy. When he suffered a serious defeat, Battle Angel disappeared.For a few years, his less-than-legal work went on hiatus. When later Battle Angel (now renamed Alita) returned to clear her past, it was believed that he died in the events. What nobody knew was that he was a magician, and escaped to another world. Another few years later he turned out to be the biological father of the child that Simon and Alita had adopted. When it became clear that she had inherited his magical ability, he tried to use her as a battery of sorts. To make matters worse he had now built Fighter, an android based on the blueprints of Battle Angel. Jessika harbored a deep hate for her biological father after this.
After Jessika got to talk to the spirit of her dead mother she found out that Yonah had been under the control of a parasite-type demon as a consequense of trying to protect Rebecka and baby Jessika from the demon.
You can't see it on the avatar, but Yonah has what some people would call a Roman nose. People who are unaware of Roman anatomical specifics would just call it a big nose.
- Schedule Fanatic When he was himself. A key sign that he is Not Himself when he returns is that he acts more erratically - which is lampshaded by the protagonists.