Luigi is the younger but taller brother of Mario
. In Paper Mario you can read his diary where he mentions that he is terrified of boo
's and that he wants to go on his own adventure. In the sequle Paper Mario and the thousand year door his wish to have his own adventure comes true. Luigi recived a letter that says Princess Eclair of the Waffle Kingdom was Kidnapped by the evil chestnut king and that they needed his help. He has to find the seven pieces of the Marvuilse compas to find Princess Eclair. In the game you can even buy a series of books based on his adventure. When Mario
talks to Luigi he tells him about how he likes Princess Eclair so Daisy
is going to have to find another man.