My maternal grandmother once gave me some advice that has never left me: when someone does you wrong, bizarrely, they will invariably hate you for it. This stems from a very human desire not to admit mistakes. Therefore if you want to salvage a relationship with the person who wronged you, you must go out of your way to be kind to them.

I have discussed my grandmother’s advice with Shaker Aamer, the last British resident in Guantánamo Bay. He has been done a terrible wrong – held for almost 14 years without charges, tortured over and over. He has never met his youngest son Faris, who was born on the very day he arrived in the notorious US military base.

And why has he been held so long? Because not only was Aamer a victim of abuse but he also witnessed the torture of others, most catastrophically Ibn Sheikh al Libi, who “confessed” falsely that al-Qaida was in league with Saddam Hussein on weapons of mass destruction. This was repeated by President George W Bush himself as a reason to go to war in Iraq – so here we are, tens of thousands of dead people later, and we know it was false. Al Libi merely told his torturers what they wanted to hear, to try to end the pain.

The Obama administration gave notice to Congress on 24 September that they finally plan to return Aamer to the United Kingdom. This triggers a 30-day waiting period, after which – when logistics and other bureaucracy is satisfied – he may come home.

What is not predictable is whether they will actually liberate him on 24 October, or some time much later on. For instance, the US announced on 25 June that another man, Abdul Shalabi, could be repatriated, yet he did not leave until 22 September, 89 days later. Aamer was cleared to come home in 2007, some 3,000 days ago, so when they will finally get around to reuniting him with his wife and four children is still uncertain.

There is one matter that is beyond all doubt: various members of the US military and the UK intelligence services will start briefing against Aamer. They will do this because they know they have done him wrong, and they hate him for it. They feel a very human urge to prove that they were justified and, in their distorted morality, that can only be true if he is a very, very bad man indeed.

They always do this. In 2009, when Binyam Mohamed was released from Guantánamo, someone at the Pentagon leaked to the BBC a classified copy of the confession tortured out of him. Binyam had been sent to Morocco where a razor blade was taken to his penis every fortnight for 18 months. Naturally he told them what they wanted to hear. To the credit of the BBC – and in compliance with the UN convention against torture – ultimately the corporation decided not to defame Binyam with this statement.

One British newspaper has already received a ‘scoop' about Aamer from a ‘former informant' for the UK security services

Before that, the US military timed a leak smearing four other British nationals to coincide with their return from Guantánamo in January 2005. It was not enough that they had spent years in detention without charge or trial; the US authorities wanted to prove that this derogation from the Magna Carta was justified because they were very dangerous people. Given that none has done anything wrong in the ensuing decade, we can now decide for ourselves whether this was true.

In Aamer’s case, the defamation has already begun. The moment the 30-day notice was given, Texas Congressman Mac Thornberry leaked the news to the Washington Post, along with a statement that Aamer was far too dangerous to be released – apparently forever. The Republicans started the mess that is Guantánamo, and it is too much to expect them to admit that it has been a disaster.

More worrying yet, one major British newspaper has already received a “scoop” about Aamer from a “former informant” for the UK security services. Of course, such a leak would violate the Official Secrets Act unless it had been approved by the spooks. The paper did the right thing, checking the story out; and Aamer was not even in the UK when he was said to have had a crucial meeting. Such care reflects the best of journalistic ethics – you do not publish devastating rumours about a person who has no way to defend himself, without checking and double-checking your source.

The government has pandered to populist opinion ever since the Leveson inquiry, proposing greater restraints on the media, yet it sees no problem when government agents themselves sneak around smearing someone – even when it concerns a powerless person held incommunicado for more than a decade, like Aamer.

Aamer understands my grandmother’s advice, and he knows that the people who are responsible for his mistreatment will inevitably hate him. He tells me that he will respond with as much kindness as he can: he does not wish to see those responsible for his torture behind bars, and he has said this to the Metropolitan police, who have been investigating British complicity in what happened. He merely wants everyone to learn from these terrible mistakes, and reinforce the rules against torture, so it never happens to others.

That is admirable. But it is inevitable that some will continue to attack him and we must hope that the media continues with the ethical approach they have shown so far. Those who wish to prove that they were right to indulge in a spot of torture are very sad and misguided people.