Glasgow Warriors' 21-3 win over Edinburgh at Murrayfield on Saturday sealed a fourth consecutive 1872 Cup success. It also marked Steyn's 100th appearance for the club, a milestone he celebrated by hoisting the trophy as captain.
Making the occasion even more special, Steyn's father Rory had flown in from South Africa, while his daughter Bella joined him as led his team out at Murrayfield.
"It was really special," the Scotland international told the Mail Online. "Running out with Bella was amazing, and my dad landed this morning, so it couldn't have worked out much better.
"I've had a few long spells injured, so you do wonder if you'll ever reach 100 games. To do it here, in this fixture, with my family present, meant a lot."
Steyn joked that his father's loyalty has come at a cost. "My mum says there's no inheritance left because Dad's spent it all on flights. But he's always been there, wherever I've played in the world. I'm incredibly grateful for that and I'll never take it for granted."
Steyn senior will remain in Glasgow for a few days before heading home on New Year's Eve, making the most of a brief but special visit.
On the field, Steyn led from the front as Franco Smith's side completed a derby double, winning by 30 points on aggregate against an Edinburgh team that struggled to get anything going across both matches.
Jamie Dobie was the standout performer, scoring twice, with George Horne adding the other try. Dobie's pace, versatility and finishing - despite being a scrum-half by trade - continue to strengthen his case for Six Nations involvement and add to Gregor Townsend's selection dilemmas.
For Steyn, the focus remains firmly on Glasgow's momentum after a demanding run of fixtures that included victories over Sale, Toulouse and Edinburgh.
"We probably didn't play as well as we'd have liked, but we're delighted to get it done," he said. "Derbies can drag you into one-on-one battles, and Edinburgh did well to slow our ball. It was frustrating, especially when we showed late on that we could break them down.
"I really feel for our forwards - Sale, Toulouse and then two Edinburgh games is a seriously physical run. But what a time to be involved. Everyone's hungry to keep pushing on.
"Franco is excellent at keeping energy fresh and rotating the squad, so I'm sure there'll be plenty of movement over the next couple of weeks."
100 up for the skipper! | BTS at 1872 Cup