Lucas was an insane,psychic child,like Ness. Together he and Ness killed many people.

The first time Luigi saw them was in an ally in episode 4, playing together and laughing, 

creating an inoccent demeanour around them. Ironically they gave hope to Luigi to fight

the butcher when they, in fact WERE the butcher, well BUTCHERS. The next time they were

seen was in the final episode shortly after the creature, the and watches had fused into

was destroyed. They had sewn all of their victims back together "like trophys", as luigi said. Lucas was

wielding a snake-like weapon while Lucas had his bat, Kirby then came and revealed that Ness and Lucas

were his progenies. After luigi supposedly killed Kirby with green fire- balls ,they dissapeared   Kirby     reappeared

at the end of the finale ,Lucas was nowhere to be found, thoughon top of Kirby's head was Ness`s blood-coverd hat...