Prosper English is the real name of Doctor Darkkon's right hand man. For the majority of Catherine Jinks's book Evil Genius he went under the alias of Thaddeus Roth. He was Cadel's therapist for eight years, the Chancellor of the Axis Institute of World Domination, the leader of a world wide criminal operation, and Cadel's persumed father.
Prosper's birth place is unknown. He has probably been to college (presuming his psychology degrees are real), and has been the notorious geneticist, Doctor Phineas Darkkon's right hand man for many, many years. But, according to English, he was the one really in charge, because Darkkon was slowly going insane. But Prosper could care less, he literally had whatever he wanted because of the Darkkon Empire's influence. But, unfortunately, when Darkkon married a woman named Elspeth, Prosper got far too involved. Darkkon treated Elspeth very poorly, sometimes even poisoning her so she couldn't leave the house. He was paranoid that she would leave him, and, ironically, she turned to Prosper for help, and it was with Prosper she (presumably) had Cadel. But it turned out that prosper wasn't cadel's father and niether was Dr.Darkkon. Darkkon was suspicious of her and had Prosper run DNA tests, which he naturally faked. However, when Prosper finished the tests, he killed her.
Role in Evil Genius
After that, Darkkon created the Axis Institute for World Domination. Darkkon was obsessed with the existance of what he called "Advanced Genes", and this college would help him get rid of the Junk People (aka, people he deemed stupid or worthless). Darkkon naturally made his most trusted lieutenant the Chancellor of his most prized venture. Prosper always thought the Institute a foolish idea, but he had better plans, and expected that Cadel would someday take it down. He had been hoping for it.
Soon after, Darkkon arranged Cadel to be raised in the care of two of his employees to specifically raise him so he would hate them and love Darkkon and trust English (alias Roth). For eight years, Prosper did everything in his power to nudge Cadel to use his technical prowess for other, less legal exploits. It was because of this that Cadel started a fake dating service called Partner Post, where he began talking to Kay-Lee McDougal (who was really a girl with cerebral palsy). When he found out about Sonja (the girl), he had a few of his agents tell Sonja about how Partner Post was fake. Finally, when Cadel did take down the Institute, Prosper was nothing but pleased. However, when Cadel attempted to escape Prosper, he was caught by the police, and Cadel spilled about Prosper's location, and when his house was surrounded, he threatened Cadel at gun point, but ultimately could not bring himself to shooting who he thought was his son.
Role in Genius Squad
In Jinks' squel, English has been brought into custody and is refusing to talk about being Cadel's father and is not taking any paternity tests. However, he does have an informant in Cadel's newest organization, the Genius Squad, which is an organization determined to bring down Dr. Darkkon's major money maker, GenoME. Eventually, Prosper does escape in his trial and is on the run, but not before making a pitstop. He and a former Axis Institute teacher, Alias, manage to kidnap Cadel and Sonja for insurance. Along with Alias, Prosper's valet Vadi (who is basically half man half fish) trek accross the country and stop at a luxurious home, assumably owned by one of Prosper's aliases.
There, Cadel manages to send a messege out to his appointed body guard, Saul Greeniaus. Knowing this, Prosper's group keep up the driving, and come to a hanger, where he learns that Prosper means to take him away somewhere. But, Greeniaus shows up and catches Alias and Vadi, but Prosper escapes. When Saul is taking Cadel and Sonja home, they find that Prosper had actually snuck into their car, and eventually kicked the three out and vowed he would find Cadel, unaware that he was not his father.
Role in Genius Wars
In Genius Wars, Prosper English has been out of the picture for quite some time now. In the beginning, Cadel has already found a university to attend, and is living with Fiona and Saul Greeniaus, who are still in the process of taking up custody of Cadel. Judith, on the other hand, has taken custody of Sonja, and has set her up with a new, high tech wheel chair. A minute into the story, Cadel has already picked up his old hacking habits for Sonja's benefit. It isn't long after that until something goes wrong. Someone messes with the wireless transmissions being sent to and from the wheelchair, and people get hurt. It isn't long after that until images of Prosper come up on CCTV cameras, when Cadel and his family deduct that he is no longer safe.
Cadel assumes he has no choice but to get back into his old routine, feverishly attempting to track down the cyber-villains. Reluctantly, his father and the police allow it. But when Cadel unknowingly slips back into his Axis Institute mindset, it's hard for everyone to tell which side he's on, including himself.