Genos has been looking for two things since the early chapters of One-Punch Man. First, he wants to find the rampaging cyborg who killed his family and destroyed his hometown. Second, he wants the power to put that cyborg down permanently. The pursuit of these things led him to Saitama. The young cyborg would go on to train under Saitama and grow significantly from the experience. At the same time, he's recognized a stagnation in his progress and grown discontent with it. He's considered a change in direction, but there's one thing standing in the way: his master Saitama.
Source：https://www.cbr.com/opm-genos-too-loyal-to-saitama/
