Quote Originally Posted by Munsu
If I remember correctly, Peter was fighting with radiation (red color), while Sylar was using something of blue color (maybe an electric charge or freezing power or something), kinda like what Peter used now. I may be mistaken though, but I don't have the first season episodes to check.
"Don't burn hot, burn bright" (Bennett to Ted, instructing him how to make an EMP instead of just irradiating everything around him).

IIRC, Ted's emp power was blue, while his irradiation power was red. As you might recall, Syler also got Ted's powers. My belief is that both Syler and Peter were using ted-powers there, but I also haven't gone back to rewatch it or anything.