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Brian showed up at Mario Brothers Plumbing one day, carrying a suitcase. Mario and Luigi were suspicious of Brian's appearance, although Brian tried to pass himself off as a seller of many different products, including pots and pans, encyclopedias and Tupperware. However, Brian eventually broke down and revealed that he was actually running away from home.
After being questioned, Brian explained to Mario and Luigi that he was running away because he believed that his parents didn't love him anymore, and he wanted them to miss him while he was gone. Mario told Brian that he should never consider running away despite his situation at home, but Brian refuses to change his mind.
Mario then told Brian that when he and Luigi were kids that he ran away from home, and told Brian of how Mama Mario constantly punished him for fighting with Luigi. After being punished one-too-many times, Mario ran away. Brian asked Mario if he had fun being on his own, to which he doesn't comply. Instead Mario told Brian that Luigi and Mama were devastated. However, Luigi revealed that he and Mama were able to enjoy themselves better and that they didn't have to share their popcorn with Mario. Mario then returned home, and was scolded by Mama, who admitted that while she didn't miss his behavior, she did miss having him around.
After hearing Mario and Luigi's story, Brian pointed out that since it was so beautiful, he was ready to barf. Mario then asked Brian if he learned a lesson, and Brian stated that he shouldn't run away because his parents would enjoy themselves too much. Mario agreed, and Brian decided to go back home, hoping to get there before all the popcorn was finished.