How was Sullivan successful being the man of the house in The Man of the House by Frank O'Connor?

He was not fully successful. though he did try his best to be mature and perform task that a mature adult would do in his position (e.g going to the pub to fetch whiskey for his mother despite his fear), upon meeting the little girl at thedispensary, she tricks him into drinking and sharing the cough syrup he was sent to fetch. When the medicine is finished, Sullivanrealizeshis mistake and does what any little boy would do in that situation, run home crying.