Something happened in the crowd at last Sunday's elimination final.  

It involved an Adelaide mother-of-six, Olivia Muller, and her nine-year-old son, Isaiah. I'd met them the previous day at the Tigers' last training. Isaiah is blind, both his eyeballs having been removed after they became cancerous – the left when he was 18 months old, the right when he was three-and-a-half.  

As the players left the track after training, the better-known of them were directed to Isaiah. They shook his hand, had a chat. The Richmond club, having been advised of Isaiah's story, had flown him and his mother across for the final. Coach Damien Hardwick took Isaiah's hand and led him into the change rooms to find Dusty Martin. Beside me, Olivia Muller said with quiet passion: "They're just a bunch of top blokes." 

Olivia has an engagingly colloquial manner. Her face is marked by the anxieties she's endured but there's a solid brightness about her. Last year, she did a 140-kilometre trek through Tanzania to raise money for a group called We See Hope.  

Olivia and her husband Craig, who has a business in Adelaide delivering fruit and vegetables, have six sons. When Olivia told me Craig barracks for the Crows, Isaiah said: "Crows, boo!", and I realised he'd been listening all along.

On Sunday, we met at the MCG. When we found our seats, this small, friendly, courteous man appeared before us who seemed to know Isaiah at a glance. It was Peter Hafey, brother of Tom, and part of the great Richmond years as the club's runner. He shifted seats to better accommodate Isaiah.

When Isaiah sat down, I watched as he swished his hands about, identifying his surroundings – the seats, the rails. I saw a busy brain at work. Isaiah follows games by listening to broadcasts. His mother had an app on her iPhone that was carrying a broadcast of the final but it wouldn't work inside the concrete bowl that's the MCG. Standing, she said to me: "I'll have to go back to the hotel to get his transistor. Can you look after him?" She was going to the Pullman, she said, "just over the road".

I immediately imagined the nightmare of looking across and the boy not being there. "Are you sure he won't wander off?" I asked. Beside me a nine-year-old voice said bluntly: "I won't wander off." That's when I "got" Isaiah - he's someone who means what he says.

While his mother was away, I called the game for him. I must admit, after the rude things I've said about commentators over the years, I sounded pretty lame. At one point I gave the score as, "Richmond 4.3", and added "27". "I don't need the last number," he said.

After his mother's return, he divided his time between listening through earphones to the transistor, and taking them off and tuning in to the tumult around him. Isaiah has a fine shout. His cry of "Go Richmond!" is like the clashing of cymbals.

We were sitting in the back row on level one under the concrete overhang. Behind us, over to our left in standing room, was a boisterous group of North supporters, one of whom was particularly loud. I was concentrating on Isaiah and not really listening. Later, Olivia told me he was saying "personal things" about Richmond players. 

A woman just along from me aged about 30 got really upset, stood up and left, but not before facing the man and calling him out. Then a second woman walked out, calling him "a f*****g jerk" for all to hear. Then I looked across and Olivia was gone.

Shocked, I looked around and saw her behind me, in the midst of the noisy North supporters, talking to the loudest one like a sister talking to a drunken brother at his wedding.

The next day I rang Olivia, by now back in Adelaide, and asked her exactly what happened. I wrote down what she said: "It took a bit to get him to calm down enough to listen to me but gently, respectfully, I tried to explain to him why people were so upset with him. He kept saying to me, "But I'm not swearing, I'm not swearing", and I kept saying to him, "I know, buddy", and I put my hand on his back in a gesture of "It's cool, buddy – I just want to have a chat". 

I'd seen Olivia with her hand around the man like she was partnering him in a waltz and directing his attention across to Isaiah. "I said to him: 'That little boy over there's my son. He's blind and the Tigers have flown him over. Those Richmond players have been amazing to him. He's upset because they're going to lose and you're yelling out very personal things about people who mean so much to him'. He said: 'But I'm not swearing' and I said: 'It's not about the swearing, buddy – it's about respect'."

It was one of the more amazing happenings I've witnessed in a football crowd. When I asked Olivia where she gets her courage from, she said: "Once you've had a kid with cancer, you're afraid of nothing."

Did the obnoxious supporter stop his bellowing because of Olivia? I only heard him once thereafter and, when I looked across, I thought his mates were standing a bit away from him.