"He has so many facets, there's a domestic and loving side to him, but he's also lethal. I really enjoy playing him because he's so complex," he said.
His character has come into his own in this series -- the second -- and on Sunday viewers saw him double cross gang boss John Boy with fellow gang member Darren.
John Boy, played by Aidan Gillen, was gunned down in a pub by Darren while sitting having a drink with Nidge.
Nidge is now looking to take over John Boy's drug empire.
To get into the character of Nidge, Tom said he had to think outside the box.
"My imagination took a great leap when I first stepped into the role, but there are definitely days when I'm be glad to get home after holding guns all day, it can be a sobering experience too.
"You realise that these people have such a short life span -- once they get to a certain level of power the outcome is ruthless and they could be easily scuffed out.
"You could walk around the corner on the street and get shot. It must take its toll living like that -- I did find that very interesting," he said.
Tom, who has starred in movies such as Translations and Becoming Jane, admitted that people are always surprised at how different he looks and sounds in reality.
"My real accent always throws people, they don't expect me not to sound like Nidge," said the Trinity College graduate, who added he enjoys sporting a shaved head for the show.
"It's nice when I don't have to worry about doing my hair in the mornings and when I look normal, like myself -- no one recognises me."
The actor has been living in London for 14 years and is currently on stage as Jerry Devine in Juno and The Paycock opposite Sinead Cusack at the Royal National Theatre.
The family man was a first-time father for less than one week when filming for season two of Love/Hate kicked off.
"Freddie was born days before we started filming, so it was a mad dash. Leaving him was tough, but my wife Claire came over for the shoot so we were all together in Dublin for 11 weeks."
Over 660,000 fans tuned in to last weekend's episode and it is expected that viewership will soar to nearly one million for the season finale on Sunday, which follows the cast in the wake of John Boy's murder.
"RTE had more faith in the writers this time around and there's a lot of hype around it now. As a result, there's more violence, but it's realistic too -- I'm so proud to have been part of it all. Hopefully there'll be a third series."