Some people might say that actually attending an exorcism was going above and beyond the call of duty, but O’Donoghue dived in. What he witnessed fascinated and sometimes terrified him.
“I was more daunted by the thought of going to see an exorcism than when I was actually there. It was the thought of it that was disturbing,” he says.
“Remember that the film The Exorcist was banned in Ireland for years. I remember growing up as a kid seeing a bootleg copy of the film. But it was shunned out of the house by my mother. The mother would come and see it and shout, ‘Get that out,’ as if the video itself was an evil entity.”
Before O’Donoghue went to Rome to see genuine exorcisms all those famous Linda Blair scenes from The Exorcist were playing at the back of his mind, he says.
“What fascinated me was that when I got there it was ordinary people going in to be blessed. It was so ordinary for them; it was nearly like a weekly or bi-weekly event. They sat there and the priest laid his hands on them and prayed. I didn’t see anything majorly extreme,” he says.
“But there was one woman whose head turned very sharply as she walked past me. She just stared at me the whole way, without blinking. And she did the exact same thing on the way out. I found that unnerving.
“I asked the exorcist how could you tell these people aren’t suffering from psychological disturbances? He told me that they had all been psychologically evaluated. So the question is always going to be open, and I think this film tries to be as unbiased as possible, as much as a Hollywood movie can be.”
O’Donoghue’s life isn’t all acting and exorcisms, of course. In his spare time he plays in a band called the Enemies home in Drogheda. The question for the other lads in the band now is, will he ever be back?
“They’re still playing without me and are probably even better without me. We were actually in the studio before Christmas recording different songs” he says.
“They came out to the party we had on set in Budapest and Anthony Hopkins got up and introduced us as the five lads from Drogheda. It was a great experience for all of us. I was home for Christmas there and we did a few gigs.”
Has his mother gotten over her dislike of exorcist movies now that her son is starring in one?
“She was just delighted I got a part! She knew I was very passionate about this particular script and she knew I really wanted it to work out. I’ve always been very fortunate in that my family and my wife have always been there to support me,” O’Donoghue says.
“As an actor you go through tough times as you try to make a career. To have their support is invaluable, they pick you up when you don’t think you can do it any more -- and there were moments when I didn’t think I could carry on.”
But that’s all water under the bridge now. O’Donoghue has just bought a ticket to the big time, and it will be fascinating to see how his career takes shape, now that he’s going head to head with the biggest stars in the business.