The dad-to-be, who is expecting a baby boy in October, said he and his wife had chosen the name as it held a personal significance to them, having met each other through online gaming.
Not only was it their first child, it would be the first grandchild and nephew for both their families, making the news extra special.
However despite the excitment surrounding the baby's arrival, a family argument around his name had caused a huge rift between the dad-to-be and his mum, as explained in a Reddit post.
"Here's where the problem comes in. My wife and I were both greatly moved by the story of Arthur Morgan in Red Dead Redemption 2. We consider him one of the best fictional characters of all time. I've been playing video games for a long time and his story is the only one to ever make me cry," he shared.
Elaborating to say it was his wife's suggestion, the pair had fallen in love with the name and as there was nothing 'wrong' or 'weird' about it, had not expected any objections. His own mum, however, was not happy with the news.
"My mother had a brother that died when I was about a year old, so I don't have any memories of him. She has been pressuring us to name our son after him. There's nothing wrong with his name, either. It's pretty common, think something like 'Robert John'. It's just not what we wish to name our sprout," he said.
"My older brother left slip to my mother that the name we chose was from a video game character and she completely flipped out. She actually drove 30 minutes to our house so she could bang on our door and berate us in person for honouring someone who doesn't actually exist over her flesh-and-blood sibling."
Continuing to say they already think of the bub as 'Arthur', after telling her that was their final decision, things quickly escalated.
"When we tried gently (and then firmly) to advise her that we respected her position but that we weren't going to budge on ours, she walked out and told us that she would have nothing to do with our son and would never acknowledge him as family."
As he's always had a good relationship with his mum leading up to the fight, he questioned if he should just relent on the name to keep the peace. His wife, however, felt they should stand firm and set boundaries on parenting decisions now.
Most Reddit users agreed he should stick by their choice, arguing pop culture inspired plenty of names and there was little difference if it was from a novel, song or video game.
"People name their kids after fictional characters from a book or show all the time. It's no different here just because the character in question comes from a story told in a video game," argued one.
"Your wife is right you do need to stand your ground. Your mother is using emotional blackmail and she can not be rewarded for that. I hope she realises she's overreacting and will come around once she sees her grandchild," added another.
Others shared the unlikely inspiration behind their own names and those of their children.
"My kid is named after two of the golden girls lol," confessed one. "I'm named after The Bionic Woman because my Dad had a crush on the actress who played her," added one.
"I was named after a Roman goddess and a street sign," shared a third.
One was more sympathetic, however, saying it probably triggered his mum's grief all over again.
"I feel for your mum, this may be grief at play here, but that doesn't give her the right to demand to name your child and there's nothing wrong with choosing a name that has a lot of sentimental value to you and your wife, regardless of where the name originated," they said.