Devan is leading an organisation called Turtle Terrorists. They're terrorists indeed, kidnapping Carrotus' princess and demanding the crown. However, this means Devan is not a leader of his home planet (in fanfics most often known as Shellion, I don't remember if it was ever mentioned officially) - possibly not even someone important for it. As a leader of terrorist organisation, he should disguise his personality in there. I also think he doesn't really want to literally KILL Jazz... I mean, he made his clone and left a warphole after going back in time. That's gotta mean something... like he was impressed with Jazz and somehow being shattered between being the good guy or bad guy. If he used his scientist skills in good deeds, he could be a hero. But then no Turtle Terrorists. ...Why would actually a geek as him lead such organisation? Why was it created? The more I try to answer with Devan, the more questions come.

...Devan Shell rocks.