I have dreamed for almost 500 days of writing this piece.

On Thursday, after 16 months in jail, my close friend Evan Gershkovich, a reporter for the Wall Street Journal, was freed, along with 15 other American, German and Russian prisoners, in a historic and complex prisoner exchange with Moscow, which received eight prisoners, including spies, arms smugglers and a killer in return.

We first began to quietly whisper that Evan, who was sentenced to 16 years in a Russian jail on bogus espionage charges, might soon be freed when, on Monday, Russian political prisoners began disappearing from their jails, one by one.

This sparked hope that they were being moved to a prison in Moscow, possibly in preparation for a large-scale prisoner swap with the west.

But we had been here before, I cautioned myself.

A previous deal was eerily close last February, a swap which would have looked similar to the one this week but would have included the opposition leader Alexei Navalny, who was then being held in a remote prison colony above the Arctic Circle. As the final details of the exchange were being formalised, Navalny suddenly died in jail. His allies believe he was murdered by Vladimir Putin to sabotage his release.

Navalny’s death had sent shock waves around the world and appeared to have shut down any hope for a quick release. Germany, which held the convicted Russian assassin Vadim Krasikov, whom Putin was desperate to free, was spooked.

The Financial Times reported at the time that “Germany’s appetite for a potential deal with the Kremlin to swap a Russian hitman in a prisoner exchange has cooled markedly.”

But Evan’s parents and colleagues never gave up. Neither did the US administration, it later turned out.

“In fact, on the very day that he [Navalny] died, I saw Evan’s parents,” national security adviser Jake Sullivan said in a press briefing on Thursday.

“I told them that the president was determined to get this done even in light of that tragic news and that we were going to work day and night to get to this day,” Sullivan added.

And so the quiet diplomacy continued.

In the meantime, Evan and I kept in close touch, as we did throughout the 16 months of his time behind bars, exchanging letters on a weekly basis.

It had become a trusted ritual for me. Every Sunday, like hundreds of friends around the world, I would send him a note. He was eager to know the weekend’s football scores of our favourite team, Arsenal, and I filled him in with the latest snippets of gossip and banter from our tight friends’ group.

Evan was advised by other journalists who were wrongly jailed before him to build a strict daily routine while in the notorious Lefortovo jail, which he did, doing pushups in the morning followed by meditations and letter writing. But books became his closest companions. He devoured Russian classics, including War and Peace, and found solace in memoirs by prominent men and women who had spent time in Russian and Soviet jails before him.

Evan’s friends tried to set up a book club with him, which hopelessly failed when we realised we simply could not keep up with his reading pace.

All along I could tell in the letters we exchanged, that he kept up his morale, never losing hope.

Yet, Evan was missing countless birthdays and weddings of loved ones, while his parents spent sleepless nights worrying about their son.

The journalist in Evan never faded. He asked his friends to send him long reads, ensuring he stayed connected to a world he had covered so well before his arrest.

It was not surprising, then, that in his mandatory clemency letter to Putin shortly before his release, Evan made a bold proposal. Seizing the unusual circumstances, he asked if he could interview the Russian leader after his release.

Thursday’s exchange resulted in the release of a range of Russian dissidents, including prominent Russian opposition figures, a feminist artist and the founder of a Nobel peace prize-winning human rights group, as well as three individuals who had served as regional coordinators for Navalny.

In a heartfelt call with his family after his release, the British-Russian Kremlin critic Vladimir Kara-Murza, whose health had been severely compromised by two suspected poisonings, admitted what many of his allies had already feared. He confided: “I was sure I was going to die in prison.”

Still, for many in the opposition circle, the exchange was always going to be bittersweet.

“The list will not be complete … Unfortunately, there are so many political prisoners in Russia, that it is not possible to change them all,” said Sergei Smirnov, the editor-in-chief of the independent outlet Mediazona.“We need to be as loud as possible about the ones left behind.”

There is Alexei Gorinov, who was sentenced to seven years for “knowingly spreading false information about the Russian army”. He suffers from chronic lung disease and had a third of his lung removed in 2016.

And Marc Fogel, an American teacher serving a 14-year sentence in a Russian penal colony after being caught with less than an ounce of medical cannabis used to treat a back injury.

OVD-Info, a Russian human rights watch group, counted that Thursday’s prisoner swap freed just over 1% of the estimated 700 political prisoners in the country.

In his first comments to the outside world, Evan appeared to be acutely aware of the men and women left behind.

“I spent a month in prison in Yekaterinburg where everyone I sat with was a political prisoner. Nobody knows them publicly, they have various political beliefs … I would potentially like to see if we could do something about them as well. I’d like to talk to people about that in the next weeks and months.”

Evan’s instinct has always been to focus on others, and I look forward to seeing the impact of his future work.

In April, just days after his arrest, I wrote that it would be of paramount importance to keep Evan in the spotlight.

Since then, the journalistic community has united in solidarity, keeping Evan’s name visible on billboards, in football stadiums, and discussed within political corridors worldwide.

Now, I can’t wait for Evan to finally be able to tell his own story.

Pjotr Sauer is the Guardian’s Russia correspondent