Generation comes from an alternative universe where Feels was the main character. The villain, instead of Eggman, was Sonic himself. Generation would always hear other voices. But he just assumed they were the badniks.

One day, Sonic had figured out how to project other versions of himself, who were all heros. Feels saw this. This drove him insane. The voices grew louder, and Feel's mind split into 3. The Id, Ego, and Superego.

The Id had a, let's say unique desire. Feed on the critters that Feels has saved. But the biggest voice was the ego. The ego called himself Generation. And one day, after an outburst from Feels, Generation took control, and Killed sonic.

However, every universe needs a sonic to function, no matter evil or heroic. But Generation didn't care. He had one goal: Kill all sonics. And he's willing to complete his goal no matter what. Deep down, he knows it's impossible. But, it gives him something to do.

One encounter, however, would peak his interest. He met a sonic, but different. He was floating, claiming to be God. Generation made quick work of him, but that encounter stuck with him. Where there others like that one? Was he like him? No matter. More fresh meat.