Yeah, didn't really need L to inspire that crazy, power-mongering ideaology which makes him eager to kill anyone who poses even a minor threat to him. He got there all on his own, and that's just because of that old adage "Power corrupts, and absolute power corrupts absolutely." I believe this is the theme of the entire manga/anime. Cause, when he loses his memory, you see that, without the influence of the power he had, he's actually a very likeable, responsible, honest, good-natured person, but as soon as he retrieves the Death Note he returns to the ol' psychopath, we all know and love.
By the way, Light is probably my favorite character in the entire the show, but that's just because I love me some crazy! Plus he's an effin' genius. And those two things, my friends = awesome, in my book.