Seven years ago, under the Eden Park lights, Malakai Fekitoa shared a brief touchline embrace with Ma'a Nonu.

This Saturday, but for a shoulder injury, Fekitoa could have made another Test debut. Again against England. Only this time for a different nation.

"I'm very sad that I won't be able to play," he said. "I was looking forward to it."

Fekitoa's first 24 Test caps were in the black of New Zealand. They came in World Cups, Bledisloe Cup encounters and British and Irish Lions series deciders.

But this weekend would have been his first for Tonga, the country he was born and raised in.

Such switches are not easy. Once 'captured' at Test level, a player's international allegiance is usually settled for life.

However, there is a route to a new nation. If a player is eligible for a second country and hasn't played international rugby for three years they can apply to play for that second nation in an Olympic sevens event.

If approved, if picked, they can switch allegiances in all formats of the game, including Tests.

It is a loophole that has taken Fekitoa full circle.

Aged 15, he was watching his cousin train with the Tonga Sevens squad. When one of the squad failed to show, he jumped in and made up the numbers.

"That experience with Tonga Sevens was where my career took off," Fekitoa remembered.

"We did a fitness session and I came first and the coach asked how old I was. I told him and he said to run around and get involved.

"Then, after a week or two, he said bring your passport.

"We went to Samoa for the World Cup qualification I think, it was my first time on a plane, I was buzzing.

"I was getting paid 400 bucks for a week at the time to be a sevens trainee. It was a lot of money for me as a student. I would shout all my mates back home, bread and chocolates and all this stuff.

"I kind of realised that rugby is for me, it was going to be my future and I chased it hard."

The pursuit took him to a top rugby school in the biggest city in New Zealand, Auckland, on a scholarship and finally to Eden Park and his Test debut.

His All Black career would have been longer, had his obligations in Tonga been lighter.

Fekitoa is one of 14 children. His father, a carpenter, died in a car crash when Fekitoa was a teenager. He has nieces and nephews, not just back on the remote Ha'apai islands, but all over the world.

Moves abroad to Toulon and current side Wasps have meant financial security for the family, but international limbo for Fekitoa, with All Black policy not to select players from overseas.

"When I left New Zealand, family and friends at home approached me about the possibility to change to Tonga," he said.

"I realised what was important and realised how good it would be to go back and help people."

So five days after playing in Wasps' final game last season, 14 years after getting asked to make up the numbers, Fekitoa was in a Tonga Sevens shirt once again.

This time, it was on the balcony of Monaco's royal palace, above the superyachts and casinos, for a promotional shoot before the Olympic qualification tournament.

"It was amazing, a really cool experience," said Fekitoa. "To be around my brother [Saia, who plays for Narbonne in France], my family, guys I grew up with back in Tonga.

"But at the same time, it was tough. Not having our gear on time, everything behind time, we wouldn't know where or what our schedule was, we couldn't find balls for training.

"All the struggle was there, but I expected it and that is why I want to hopefully go back and slowly change the mindset.

"I want to pass on whatever I have learned from my experiences with the All Blacks and here with Wasps."

Tonga lost three out of four group games. They fell well short of making Tokyo, but Fekitoa's participation clears him to play for Tonga in the XV-a-side game.

Lopeti Timani, who won 12 caps for Australia, also took part and could win his first Tonga Test cap at Twickenham on Saturday.

There would have been others.

Bristol's free-running full-back Charles Piutau, who won the last of his 17 New Zealand caps in 2015, wanted to be in Monaco. But he was double-booked. Bristol's Premiership play-off semi-final against Harlequins took precedence.

And his chance to switch, as it stands, is gone for another three years.

It didn't used to be so hard. Jamie Joseph and Va'aiga Tuigamala, both All Black greats, played for Japan and Samoa later in their careers without the need to jump through an Olympic ring.

And it might not be as difficult in the future. Later this month, World Rugby will vote on a rule change that means players can opt to represent a second country, providing they have a "close and credible link" and three years have passed since they were last capped for their first.

Either way, Fekitoa says there are plenty more players who want to return to strengthen nations that have given the game so much.

Players who want to pay back in ways that don't involve wiring money from Europe or Japan.

"There are a lot of people who want to do it," Fekitoa said.

"Surely we can do something to grow the game so we don't see the All Blacks against Tonga being a 100-point difference.

"It is not going to affect England or the All Blacks - there is always new talent coming through. But to grow our game on the world stage, for the World Cup, we have to have the best players playing.

"We want to go back, not only to play, but to build something for the next generation. We can finish and the next guys can come into a stable environment."

In a game in which the laws are constantly being fine-tuned, a 'homecoming' tweak to make it easier for Fekitoa and others to start that legacy, could be one of the most impactful of all.