Lucas is the silent protagonist of Mother 3, the final entry of the Mother series. He lives with a happy family consisting of his mom, Hinawa, his dad, Flint, his loyal dog, Boney, and his twin brother, Claus. The game begins with him as a timid but happy young boy while he visits the mountains with his family. But what started as a relaxing family outing soon turns to tragedy...

In Mother 3, Lucas has blonde hair and a yellow and red T-shirt. He wears shorts and orange sneakers and blue shorts. Various characters refer to him as having a "baby face."

Though Lucas doesn't speak throughout the game, his actions reveal that he is mostly shy but also friendly. He's willing to put himself out for others in need, even if it sometimes means endangering himself. He doesn't fight unless he has to, preferring love over violence. But despite his shyness, when he is faced with a tough or scary situation, he puts on a brave countenance and faces his opponents head on. In battle, he is an adept user of PSI and one of the only people able to use the devastating PK Love spell. He can also use various buffs and debuffs to help out the rest of his team. Even without his PSI, his high offense stat makes him one of the best physical attackers in the game. His primary physical equipment are sticks and baseball bats, reminiscent of main characters from Mother and Mother 2.

In his travels, Lucas makes many friends. He is close with many of the villagers of his hometown of Tazmily Village, who often greet him with food or advice. He makes friends with the mysterious Magypsies, magical beings who teach Lucas how to use PSI moves. He also runs into the princess Kumatora and the thief Duster and quickly befriends them. He also rescues and befriends a monkey named Salsa. In fact, his only real enemies are the monsters that attack him and the one true villain of the story...

Lucas also makes appearances in Super Smash Bros. Brawl and Smash 4. He retains his ability to use PSI in the fighting games, granting him the power of strong, devastating smash attacks. His rope snake also makes an appearance in the game, able to hook on to enemies and ledges from a distance. His unique second jump and PK Thunder attack also allow him to recover to the stage easily. His final smash, PK Starstorm, obliterates enemies with giant glowing meteors from above.