He would have a role similar to Asgore in Undertale, in that he is forced to fight you. However, he is more of a villain, after years of neglect and suffering at the hands of humans. If you really, truly, apologized to him for all you did, he might change his mind...after all, a toy's purpose is to be played with, and you provided that to him for years...
Lore: Legorath is a old LEGO minifig, worn down from years of use...He's been forced to live in a mech suit due to all of his wear and tear. He fights for the sake of all of his fellow LEGOs, never to be forgotten again. He bears a scar shaped like the sun on his chest, taking it as his symbol.
