A Traitor's Fate
A Traitor's Fate is a post-game level in the Bowser Jr.'s Journey mode of Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey.
Some time after the defeat of the Best Fitness Friends and the thwarting of Fawful and the Dark Star's plans for the Mushroom Kingdom, a trio of Goombas at Bowser's Castle discuss the events, eventually coming to the subject of the minions that defected from Bowser and fought against him. Private Goomp, Corporal Paraplonk and Sergeant Guy are walking by, but stop upon hearing this change of subject. The Goombas then notice the three and berate them for betraying and locking Bowser in a safe, despite Bowser having pardoned the trio for their treason. The Goombas state that the three of them must earn back their trust and then shun them. Shortly after Bowser Jr. walks by, clearly bored, and demands the minions fight with him. When they refuse, he suddenly recognizes them as having defected to Fawful, immediately concluding that the Malatone Formula:X influenced them in some manner. He then forces the group to fight him anyway, despite their protests.
The level consists of four battles, with each of the trio - Sergeant Guy, Corporal Paraplonk, and Private Goomp - acting as captain in that order for the first three battles, with underlings of the same base enemy type (i.e. Shy Guys, Koopa Troopas and Goombas). The fourth battle has Bowser Jr. fight the whole trio, who battle alongside two of their underlings; Private Goomp and Corporal Paraplonk act as captain and first officer respectively, with Sergeant Guy as one of the troops.
After defeating them all, Bowser Jr. compliments them on the close fight and then makes Private Goomp and the others his "sparring partners" for life, demanding they not leave the castle in case he wants to fight again. As the trio try to talk him out of it, he demands they give him one more fight, only to immediately change his mind and suggest they go until he wins 20. All the while, his "best friend" Captain Goomba watches the scene with barely masked relief, though he flees upon Bowser Jr. asking if he wants in. The three then join Bowser Jr.'s team.