Marco Chery is the twin brother of Donna Cherry - Delwis's Pokemon Professor. Even since he was a child, he's dreamed of being the first man on Lisin (Mars) - and that dream recently cane true a few years ago, as Marco is currently an astronaut, living on Lisin to research extraterrestrial Pokemon. He's an avid lover of space and the cosmos, but in general, he's knowledgeable, down-to-earth (ha), and caring, just like his sister. 

He has a major flaw, though - due to a certain incident in his past, he's become untrustworthy of strangers, always assuming the worst of people he doesn't know.