People have often assumed that Percy was based off of Tedd from Dan Shive’s El Goonish Shive. While I am a fan of EGS, having read it since the Painted Black arc in 2003 (incidentally, it was the first webcomic I started reading), I had the design and character for Percy figured out long before I ever laid eyes on Tedd. So no, Percy is not based off of Tedd, they just happen to both be glasses-wearing, semi-long-haired, somewhat stereotypical young mad scientists.
This comic is actually lovingly taken from EGS’s very first comic (please don’t kill me Dan!). I edited Elliot out and replaced a generic picture of Percy from the Welcome to Greenpath arc. I left all of Tedd’s lines the same and made Percy work around them. As for whose mad science is actually cooler, my vote has to go with Tedd, but I would be totally flattered if you choose Percy!