The two men met for the first time as Sullivan drove a train carrying goods from Kaikoura into Christchurch.
It was the first train into the city since November's quake.
Sullivan recalled how he spent the night of the quake trapped. About 25 minutes after the quake struck, he escaped up a hillside, fearful of tsunamis hitting the coast. The rest of the night was spent near the train.
"Definitely the blood was flowing," Sullivan said.
Having moved to Christchurch in June 2011, the Australian-born train engineer had experienced quakes before and knew how to act.
But it was Brabym on the other end of the line that saw him through.
"Not knowing you at all, all I was worried about was your family," Brabym, 51, told Sullivan as the pair met today.
For Brabym, who took a week off work after the ordeal, today was an important emotional step.
"Usually when guys get home, we say, 'Catch you next time'. We didn't get to say that, so this is a big deal for me. It's closure for me, getting to see you here," he told Sullivan.
Sullivan said he had no second thoughts getting behind the controls again and was glad to drive into Christchurch, which he said was a "symbol of how you could overcome these things".
Following November's earthquake, there were around 60 major damage sites, including tunnels, bridges and embankments. The railway was buried under more than 100 slips and landslides, with around 60 bridges suffering damage and repairs required at more than 750 sites.
Earlier in the day the train was driven from Picton to Kaikoura by KiwiRail locomotive engineer Paul Foskett, who had just finished his shift 15 minutes before the quake struck and had started driving home to Blenheim.
His car was thrown across the road and he witnessed other cars drive into holes created by the quake.
Foskett's colleagues spent a worried night searching for him, and it wasn't until daylight that he was located sheltering in a farmhouse.
He spoke to an enthusiastic crowd at Kaikoura about his experiences and how he thought he'd never have returned to the Main North Line given the damage.
"How wrong was I?" he said.
Transport Minister Simon Bridges said the return of the key freight service was "an immense achievement".
"[It] will take pressure off the inland routes while helping with the rebuild of State Highway One during the day," Bridges said.
The return of rail, even in a limited capacity, will take around 2000 trucks off the road each month, Bridges said, building to 4000 trucks when the line is fully operating again by the end of the year.
