Fan character question

Eeeh, I couldn't find the question section, but I have a feeling this could be in a better place, buuuuttt..

I remember a rule about people being unable to rip entire characters from a show, but I wanted a character that would technically do that either way he was brought here... Let me explain. I wanted to bring an evil technology genius, who's actually very clumsy, lacks common sense, and is basically as strong as a scrawny teenager because he is, over. I know I couldn't take certain things in the history or alter it to fit to the Soul Eater universe, but ability wise, all he's good at is being a lackey and building complex machines.

 (The only reason I want to bring him over is because I have an actual fan character that I could easily edit the history with, and they would be a team). 

The character I'm talking about is Jack Spicer from Xiaolin Showdown, he lives in his parent's basement, and doesn't have much going for him n whatnot, so not necessarily sure how much I'd be able to edit his stuff to fit in with the Soul Eater universe, it wouldn't be much because he doesn't have much...

So I just wanted to know the limit of how much you could use use as from a show to build your character, because I like his personality, his unrealistic goal, and the fact that he's technical savvy, but I feel If I keep the things I like it would feel like I didn't add much originality....

Taking 1:1 rips isn't allowed. Basing a character off of something else, on the other hand, is fine. Just make then different enough that it's original.