Roper reached out and grabbed him through the handrail.
He held the full weight of the stranger in his arms until the next person came along to help, Roper said.
"It seemed like forever, it would have been only seconds, but it seemed like forever."
There were moments when he thought he was going to have to let go due to a previous back injury, he said.
"I couldn't turn around to see or talk to anyone because I was hard up against the rail, but I was so thankful that other people came to help me and could see what was happening.
"There would have been five of us that pulled him back over the rail."
They used a tiedown to pull him up, he said.
"We basically held him down on the footpath until the police turned up and then the ambulance."
It was a harrowing experience for the 34-year-old.
"I was in shock for hours afterwards," Roper said.
"I couldn't concentrate, my hands were shaking. I didn't sleep properly that night.
"I'm just a normal person and I hope anybody else would have done that.
"I just happened to be the first one there."
Roper said he just hoped the man got the help he needed.
"No matter what they have been through, it's not the way."
His partner Skye Gibb, who remained in the car with the young children, said it was an overwhelming situation.
"He is really good under pressure," she said. "I was really proud of him."
Gibb said she would really like to see how the man was going in the future.
The man later wrote a few words thanking those who helped him and shared them with police who in turn shared them on Facebook.
"To Police, Ambulance and Fire who turned out, my thanks for being there to either support me, or worse pick up the pieces. I know your job is hard and for anyone who thinks otherwise, you are crazier than I.
"No-one knows unless they have travelled the path what depression can do, what a once perfectly happy person suffers or believes when in a cycle of depression and self hate.
"Even I who has been there find it hard to explain.
"I am grateful to staff at Ward 17, who let me be, made sure I knew they were there should I want to talk, listened when I did and hugged when I needed."
WHERE TO GET HELP:
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call police immediately on 111.
OR IF YOU NEED TO TALK TO SOMEONE ELSE:
• LIFELINE: 0800 543 354 or 09 5222 999 within Auckland (available 24/7)
• SUICIDE CRISIS HELPLINE: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• YOUTHLINE: 0800 376 633 ,free text 234 or email talk@youthline.co.nz or online chat.
• NEED TO TALK? Free call or text 1737 (available 24/7)
• KIDSLINE: 0800 543 754 (available 24/7)
• WHAT'SUP: 0800 942 8787 (1pm to 11pm)
• DEPRESSION HELPLINE: 0800 111 757
• SAMARITANS – 0800 726 666.
