About Kurtis, Defender of Earth!
A place for some pictures, information on the character as he existed in the source material.
Only image a google search could find for him.
http://en.wikipedia.org/wiki/List_of_Disgaea_characters#Kurtis
Also a better picture of them there... wish there was more out on the web. Wikipedia also includes his Prinny Form.
Kurtis, Defender of Earth is not an actual "Defender", at least, according to the Real Defender of Earth, Captain Gordon, and his side kick Jennifer. However, he has been known to do a lot of good, often taking up missions before Captain Gordon (Possibly ones he was too busy to do, or so I gather between the lines, though it is never really said plainly).
Kurtis, it is revealed, is a brilliant scientist, and had been a peaceful man until his wife and son were both killed in an experiment gone wrong, one which destroyed the majority of his body. He himself built new Cybernetic parts to replace those that were lost, and he came to hate Captain Gordon, who did not save his family. (It's said by Kurtis that Captain Gordon did not save his family. Though it is never really established that he was THERE to save them. One guesses however that he was doing a missing in the area, or perhaps was related to the accident somehow though by the depth of his specific anger at Captain Gordon.)
When Captain Gordon was sent to the Netherworld to slay the Overlord, Kurtis joined with the Earth Defense Force under General Carter. He became the go to man in his forces, sent out to deal repeatedly with the troublesome Captain Gordon, and his demonic master Laharl.
During one of these Confrontations, he kidnaps Jennifer, Captain Gordon's side kick, and lures them to the space battle cruiser Gargantua.
It is there, he fights his final battle as a human/cyborg, killed by Captain Gordon. While he repented for his misdeeds before his death, it wasn't enough to save his soul.
Kurtis reappears later, stuck within the body of a Prinny (The zombie Penguin things that bad humans become until they work off their sins). During a crucial battle he returns to lend his support to his rival Gordon, and Laharl's allies. It is then he takes the title truly, Defender of Earth. Together Kurtis helps the group assault Celestia itself, until finally they face Seraph Lamington himself....
Kurtis is known to the group for his scientific genius, his determination in battle, as well as his sardonic wit. He doesn't get along with others very well, even after he turns "Good". And while he no longer hates Gordon, and will fight effectively at his side, it seems he would rather do things by himself if given the choice.