Mickey is a complex character, rapidly displaying many different facets to his personality throughout the 6 seasons of his appearance. He is violent, but never without reason, even if those justifications range from acceptable to tenuous. He generally seems to have physical violence. He is seemingly self-serving. He at first refuses to engage in anything deeper than a friend with benefits with Ian, but displays surprising tenderness for the boy.
He's dropped out of high school, and has admitted himself to be "fucked for life". Despite him announcing to everybody at the end of season 4: "I'm fucking gay, big ol' mo", he has multiple heterosexual encounters throughout the series, even post-coming out. This shows his insecurities about his sexuality and the macho image he puts on to hide it. His behavior is equally erratic. He is fairly self-aware. However, he displays a severe inability to express himself. His contradictions can be attributed to his upbringing: Mickey has been raised with the expectations of the violent nature of the Milkovich family.
He truly cares for his family, being close with his sister Mandy Milkovich and jumping to her defense, when she's threatened. After his relationship with Ian was revealed to her, they seemed closer in regards to him. While he initially did not care for his presumed son Yevgeny Milkovich , he came to care for him once he accepted his sexuality and took an active part in his life and being worried when Ian abruptly took him.
Mickey also expressed joy in seeing his son again while he incarcerated. As the seasons progress, Mickey progressively displays care for Ian. It is obvious that Mickey is starting to develop feelings for Ian but is trying not to and fails. It is worth mentioning that his care for Ian extends somewhat to the Gallagher family as a whole.
A prime example of his care about the Gallagher family is when Mickey searched for Ian and told him that it was fine if he never wanted to hang out with him, Mickey, again that was fine but told Ian that he needed to call his family and informed him of the chaos that had ensued in his absence. Mickey has encounters with the Gallagher family, in somewhat wholesome but mainly just funny ways. He talks to Carl about drug dealing, and Frank and Mickey talk about guns in one scene.
