"Parent Trap" actress Natasha Richardson died from blunt force trauma after a freak skiing accident in 2009.
Micheál and his brother Daniel were just 13 and 12 years old, respectively, at the time.
Richardson's mother, Vanessa Redgrave, told the Daily Mail that Micheál made the decision to remember Richardson.
"That wasn’t because he wanted to avoid his father's fame, which is enormous. He wanted to hold his mother close to him — because she was a remarkable actress," said Redgrave. "Absolutely remarkable."
In the years after Richardson's death, Micheal struggled to move on. A self-described "mama's boy," he began drinking heavily to cope, he told The Sunday Times in 2015.
"Everybody said, 'This kid has lost his mum, that’s where the problem comes from.' And I was like, 'No, it isn’t, I just like to party.' But looking back, I realize it was a delayed reaction."