In Los Diablos, Mikey meets Frank and they argue over who should win with Frank mentioning to Mikey on why he should be the ideal person for hobo loco by stating he buried "a wife", "a mother who never loved him", and "cancer riddled girlfriend". Mikey is impressed but mentions his own shortcomings.
In The Hobo Games, he competes with Mikey throughout the games. In the end, they both lose to another competitor and Mikey wants to continue his association with Frank but the latter walks off disappointed.
As of We Few, We Lucky Few, We Band of Gallaghers!, six months have passed and Mikey has injured his leg after getting hit by a train. He has more or less recovered and while begging, he bumps into Frank who he teams up with in a scam in exchange for pills. They steal couch cushions and celebrate at the Gallagher Household, where they get high on pills. Mikey makes himself at home, as the Gallagher children are confused on his identity.
In Sleep Well My Prince For Tomorrow You Shall Be King, Mikey takes to living at the house becoming roomates with Frank. Mikey is told by Debbie if he wants to live there, he has to pay rent. At the end, he uncovers Debbie's scam and blackmails her into giving Frank control of the house or he'll destroy her receipts. She complies.
During Which America?, Mikey reveals to Frank that he has kidney disease.
In A Little Gallagher Goes A Long Way, Mikey resolves to go back to prison in order to receive free healthcare. Mikey beats farewell to Frank and walks off address is an officer before promptly hitting him in the face. Mikey then surrenders and is arrested with Frank watching him drive off.
- He is one of Frank's few friends.
- He is one of the few people to beat Frank at his own game of scamming.
- It is implied Mikey might not be his true name, since he stated that he stole that off someone.
- In Season 10, he is now living at the Gallagher Household.
- He implies he has children.
- He has revealed to have kidney disease.
- Frank calls Mikey his best friend.
- His father committed suicide.
- Like Frank, Mikey went to college and has been to prison.