Grape was a low-class Saiyan from a dark timeline where Goku never made it to Earth. He was a follower of Turles, and when the Tree of Might was planted he chose his moment to betray his commander and take the delicious fruit for himself.
When he bit into the fruit of the Tree of Might a great change came over him, and he transformed into a great ape, but his fur was now purple, and dark lightning crackled from his head to the tip of his tail. He didn't remain in this Grape Ape form for long, as within minutes he had transcended into a Mighty Super Saiyan, a SSJ form only possible with the Tree of Might's fruit. His long purple hair stood erect, and his skin became like the bark of the great tree that gave him his power. Unfortunately the sheer force of his transformation shattered causality, and he was sent tumbling through time and space into the true timeline.
He awakes in a strange new world, and though he had eaten the fruit of the tree, he was now filled with a new hunger, a hunger to test his new abilities.