I got the paragrapf from wikipedia and put the spoilers myself.

Fry is a dim-witted, immature, slovenly pizza delivery boy who is frozen just after midnight on January 1, 2000, reawakening on New Year's Eve, 2999. He gets a job as a cargo delivery boy at Planet Express, a company owned by his only living relative, Professor Hubert J. Farnsworth. His love for Leela is hinted at from the first episode onwards. Through actions he takes in the episode "Roswell That Ends Well", Fry unwittingly becomes his own grandfather. This act causes him to lack the delta brainwave, which results in him being immune to the Brainspawn's powers.