Tom (34), who lives in the UK with wife Claire Cox and their toddler son, said his own family in Dublin weren't shocked any more by his portrayal of the hoodlum. But that isn't the case with Claire's family.
"My extended family would be (shocked) because they are from Peterborough and don't know Dublin well. They're slightly alarmed by it. But they enjoy it. I suppose it's that gap between who you are in real life and what you are as a character.
"People sometimes say, 'It's hard to believe it's you'," Tom said. And his screen persona will be unnerving more in-laws in the UK in the coming months when Love/Hate is screened by Channel 5.
Having just wrapped the fourth season of the crime drama last week, Tom was back at work in Dublin yesterday rehearsing a new production of Mark O'Rowe's one-man show Howie The Rookie, directed by O'Rowe himself.
It opens at the Project Arts Centre on June 17, and stars of Love/Hate are expected to see his performance, along with fans of the TV show.
But O'Rowe said this could be a mixed blessing. "It takes people who don't go to the theatre a while to realise the actor is there in front of them, and trying to performm," he said.
"The good thing is that Tom will be in character and talking to the audience so, if he needs to tell them to shut up and sit down, he can."