Mario & Luigi: Royal Pain is the next installment of the Mario & Luigi series. There is not an official release date for it yet, but pressure for the game ensured it will come out after the next game in the series.
Mario: Our brave plumber in red, Mario is accompanying Luigi and Toadsworth to help stop a massive war from breaking out,
Luigi: The deuteragonist, like he is most of the time, Luigi has returned from a ghost hunt with Professor E. Gadd. With Luigi so tired, can he keep up with the action?
Toadsworth: The sidekick for the game, Toadsworth is attempting to prove he is still good enough to be Peach's mentor by joining Mario and Luigi on their adventure. An evil spirit residing within him causes him to turn giant whenever he gets mad, rather than stressed.
Peach: After she had finally arrested Bowser, she thought the chaos was over for good. Peach attempted to join Mario and Luigi, but Toadsworth persuaded her to stay. She and Daisy are tricked by the villain into starting a war.
Daisy: Although she starts out as the main antagonist of the game, it is learned she believes that Peach has captured her grandparents.
General Troopa: The Paratroopa commander of the Mushroom Kingdom's army, he will stop at nothing to declare war due to his long time grudge against Sarassaland.
The "T" Gang: A shady group of Toads vandalizing the castle.
Bob: A Bob-Omb who is still hypnotized by Fawful. Although he is a one-man army, he has built a mobile fortress.
Nijam: An evil spirit within Toadsworth who causes him to be turned into a giant, raging lunatic whenever he is angry. He is eventually tamed by Toadsworth, and allows Toadsworth to be in charge when he turns giant.
Crog: An assasin sent by Toadamant to kill Mario, Luigi, and Toadsworth, to prevent Peach from discovering they weren't being held hostage.
Daisy: The Princess of Sarassaland, who appears to be attempting to declare war on the Mushroom Kingdom.
Toadamant: He is the one who persuaded both of the princesses that the other one was holding the other hostage. He claimed to Peach that Daisy had captured Mario, Luigi, and Toadsworth, meanwhile, he had actually held Daisy's grandparents hostage. He had been planning revenge against both kingdoms for years.
Defurst: The first Goomba Mario ever stomped on. After making a perilous journey across the land to reach the Mushroom Kingdom and inform them of Bowser's plan, he was stomped on by Mario, and left in a vegetive state. Toadamant helped him recover, and helped him carry out his plan to get revenge. Defurst is the true main antagonist of the game, as well as the final boss.
Mario is invited by the Princess to celebrate a year of peace, now that Bowser had been arrested for good. Mario can go around and try out different booths, as well as Toadsworth's Training Booth, which is mandatory to go to before going to any other booths. It is there that you fight a Battlebot, and are taught to fight. Once Mario arrives at the castle entrance. Peach greets him with a hug, and talks about how peaceful everything has been. They look at the sunset, about to kiss, when all of the sudden Luigi falls out of the sky and lands on Peach. Mario gets mad at Luigi, and is about to attack him, when Luigi, in a panic, points at the sky. A blimp with the Sarassaland symbol on it shows up. Peach waves, thinking Daisy has come, when all of the sudden, it drops a bomb. Soldiers from Sarassaland start attacking the kingdom, tying up residents and taking them to their boss. Mario and Luigi fight with the soldiers and free residents, until they encounter an oversized guard. The guard laughs at them, about to attack, when suddenly, Toadsworth appears and wacks the guard in the head with his cane. He joins Mario and Luigi to help clear out the rest of the area. After clearing out the Mushroom Kingdom of guards, and defeating the boss, everyone starts wondering why Daisy's soldiers attacked. A shaded figure then stands on top of a building, and announces that Daisy is declaring war on the Mushroom Kingdom so that she can expand her land. Luigi tries to throw a rock at the figure, but the figure quickly retreats. Peach then approaches the three, and asks Mario and Luigi to go stop Daisy, and scolds Toadsworth for fighting, but Mario and Luigi back him up, and she decides to let him go with them. As they leave the gates, the figure stands on top of it, without them knowing, watching them exit the kingdom, and says, "And so, begins the demise of this pitiful land."