Cheo

cheo is a important character that is needed to succeed the game, as without him, you wouldn't be able to shapeshift into forms necessary and to slip through cracks, making the game impossible.

backstory
cheo was not born from a family, rather created by his great great grandfather and before he could finish, he died of a heart attack. cheo's great grandfather also tried to fix it but failed before passing on. cheo's grandfather and twin both worked on him for a while, before finishing him. a hour after activation, cheo's entire family got wiped out except for him and crag, the name of his twin. crag soon died afterwards after a heart attack, so cheo has no idea how he was made until the events at the end of the game where the grandfather is reformed and his memories flood back.

when he was 25, he stumbled uppon the mushroom kingdom and made himself at home. he had 2 friends, a blue and a yellow toad. when he stumbled upon mario, mario introduces himself. after 2 days of knowing and living with mario, cheo decided to let his secret be safe with mario; he can red minds of almost anyone except for someone harvesting the power of the purple diamond's concrete shattered insides in the middle of the dimensions (bowser and his baddies.). mario then asks him if he has any other secrets. he reveals that he can shapeshift into shapes in a similar fasion to paper mario sticker star goombas. then, he agrees to help mario through acts similar to paperization (shapeshifting as mentioned before) and slip through cracks in walls for secret items and exits, and it's the players turn to decide cheo's fate from then on.

trivia

 * cheo is often rephered to "BSS" (BLUE SMILEY STAR).
 * cheo's grandfather has actuall backstory unlike cheo's great and great great grandfather.