Held at Guantanamo for 14 years without charge, the last Brit to be released from the prison camp told ITV News he broke down in tears when he first laid eyes on his children.
A father-of-four, Shaker Aamer's youngest son Faris was born the day he arrived at Guantanamo in 2002 - meaning their first meeting was after he landed back on British soil.
His eldest, Johnina, was just four when he was arrested - meaning she only has limited memories of her father before his arrest, while her younger brothers Mikhail and Said were aged just two and one, and do not remember him at all.
Mr Aamer told ITV News his first instinct was to "grab them and hug them" - but said they were wary of the man who, for all intents and purposes, was a stranger to them.
"It's 14 years, you know. For them I'm a stranger, a total stranger," he said.
"So they were acting with me like strangers, yes their dad and all that but they still don't know nothing about me and it was hard. I held myself a little bit but then I started crying.
"I just grabbed them and hugged them but they were just standing still. That's what broke my heart."
The worst moment, he revealed, was when he addressed the tallest of the boys, assuming because of his size it must be the eldest, Mikhail - but it turned out to be Faris, the son he had never met before.
Now, he said, he wants to focus on learning how to be a proper father."It's still painful. I was father but I wasnt a father, you know - a father by name only but not truly," he said.
"It's hard for me to practice being a father right now, because truly the way I've been raised up and the way they are is totally different. We are in totally different worlds.
"And I don't want to fail, I don't want to be a failure with my kids, because i know things like this happen - in fact, there are some brothers who have problems with their kids because our mentality, the way we've been set, is different than theirs.
"But I have a lot of help around me which will help me get there."It comes after he told the Mail on Sunday of the moment he saw his wife for the first time after his release - saying it had "washed away" 14 years of pain.
He met his wife Zineera shortly after leaving the plane in October.
That instant washed away the pain of 14 years. It washed away the tiredness, the agony, the stress. It was like it no longer existed.