Possible Clues:

• Super Mario brother
• Mario's brother, in video games
• ___'s Mansion (game in the Mario franchise)
• Mario's twin
• Brother in a video game franchise
• Italian bear touring island by India
• Italian form of Lewis
• Character who can be played in every installment of 26-Down
• Lover of Giorgetta in Puccini's 'Il Tabarro'
• 'Mario Is Missing!' hero