Sunday Times:
Much of that diplomacy will have been carried out by Michael Kennedy, who for many years has acted as an agent for both men. Kennedy is known to have been deeply put out by the falling out between Keane and Quinn, whom he adores equally, the way a father might his two sons. In the aftermath of the 2002 World Cup he tried to organise a reconciliation. One attempt, a planned handshake at the end of a Premiership match between Sunderland and Manchester United, backfired when Keane was sent off for elbowing Jason McAteer.
The animosity has mostly come from Keane's side. He called Quinn a "muppet" and a "coward" over what happened at that World Cup, but the jibe that will have stung most and struck the greatest chord was his description of Quinn as a "Mother Teresa" over his much-publicised decision to donate the proceeds from his testimonial to children's hospitals. Quinn's response was largely to analyse Keane analysing him, rather than return the barbs. "Roy will have me down as too soft, too nice, too much of a goody goody, too damn happy with my lot," he once wrote. "For him, I'm football's version of the Singing Nun. But while we've never been close, Roy and I have been through a lot together. For the rest of our lives to be about blame and recrimination would make a mockery of the good days."
While Quinn's tone has been conciliatory by and large, he did launch a fierce attack on Keane last November after Manchester United's injured captain caused a storm by castigating several of the players on MUTV after a heavy defeat at Middlesbrough.
Nine months on, this is the man Quinn wants to lead the revival at Sunderland. That they can do business together shows how big the prize will be should their joint endeavours succeed.
The Indie:
For the best part of an hour on Friday in the media suites at the Academy of Light, Sunderland's state-of the-art training complex, Niall Quinn bobbed, weaved and danced around the subject. "When we're over the line, we'll let you know," he repeated ad infinitum. Roy Keane this and Roy Keane that, his inquisitors jabbed away at him. Not once was the Sunderland chairman goaded into mentioning the name of the man he wanted to not so much get over the line as to sign on the dotted thing.
With the Lonsdale logo on the sponsors' board behind him, the big man floated like the finest of pugilistic butterflies. It brought to mind Roy Keane watching Ali while flying with the Republic of Ireland to their 2002 World Cup training base and resolving to stick to his principles, like the Vietnam draft-defying king of all the heavyweights.
Keane had just about had his fill of what he subsequently described as his country's "third world approach" to international football: of rounds of cheese sandwiches for the players instead of bowls of pasta before vital World Cup qualifiers; of haphazard travel arrangements; of drinking sessions in between matches. Getting to Saipan and finding rock-hard pitches, no training kit, no electrolyte drinks and no goalkeepers involved in five-a-side matches added up to the final straw for him.
It was then that Keane vented his spleen and ended up telling Mick McCarthy: "I didn't rate you as a player, I don't rate you as a manager and I don't rate you as a person. You're a fucking wanker and you can stick your World Cup up your arse."
Perhaps one reason why Keane now stands on the brink of accepting Quinn's advances is a desire to see precisely how he would rate against McCarthy in the football management game. If Quinn does succeed in getting his man, the old adversaries would be lining up on the same Championship bill at Molineux on 25 November and at the Stadium of Light on 7 April.
Keane has his history with Quinn, of course. He was distinctly unimpressed when his team-mate offered his instant support to McCarthy when the brown stuff hit the air conditioning in the dining room of the Hyatt Regency in Saipan. He has referred to Quinn in print as "a muppet", "a coward" and, less than affectionately, as "Mother Teresa". The fact that Keane is considering launching into a new career in working tandem with the Sunderland chairman suggests how much the challenge of the management job on Wearside appeals to him.
The Mail:
News that the man in question was his former Republic of Ireland team-mate Keane then came out late on Wednesday evening, much to Quinn's annoyance.
Quinn was therefore reluctant to discuss the situation at a press conference on Friday morning but said: "We are in negotiations with someone who has not yet said yes and has not said no.
"We are not putting time frames or deadlines on it. There has been a lot of stuff written in the past couple of days about us being over the line, it's not true. Nothing has collapsed but nothing has been finalised either.
"We are still comfortable that it is on track. It is long and protracted but we are at a point where there is a will there for the man to come, we just have to provide everything, and evidence of it which we are doing now, and we will see where it goes.
"If it comes off it will be great. If there wasn't any interest we wouldn't be where we are today, so that is encouraging.
"I am glad the person we are talking to would have the same opinion as me that this club can go far higher than it is at the moment.
"If we reach a point where it is a yes or a no we will tell you immediately, we cannot have unconnected parties telling everybody the club's business.
"We know the team drives the club. The best thing for this team is to get a top manager that will allow me to carry out the role I always saw myself doing in bringing on the rest of the club.
"We are in a position now where that might happen. If it doesn't we will let you know and look elsewhere."
Quinn did not refer to Keane by name but added that the would-be manager "will be a world-class attraction any club would be proud to have."
Ferguson:
"It's a bit earlier than I thought.
"But in some cases in football, tomorrow may never come.
"The opportunity is there to take the job and, if he is taking it, maybe that's uppermost in his mind. You don't want to be out of the game too long.
"I got the same advice when I was quitting playing, in case these moments pass you by.
"Sunderland is a great club with a great history, a fantastic support base and a good stadium.
"Everything is there and apparently they've got a fantastic training ground. It's got most of the things correct about them.
"It wouldn't be easy, I don't think being a manager is today, it doesn't matter where you are.
"The way football is structured in terms of the media, agents, freedom of contract and players' power nowadays, it's completely different.
"It's not easy getting a job nowadays."
Steve McClaren:
"He'll make a fantastic manager.
"He's got all the qualities. I was fortunate enough to work with him for three years, and even then he was demonstrating his leadership qualities, off the field as well as on it. When you get to know him, he's got other great qualities which make him potentially a very good manager. He's got a good football brain, he can see and read the game. He knows what he wants and what to expect from players. He sets standards and demands them. His football intelligence is also very important when you become a manager."
Kevin Kilbane [former Ireland team-mate and Sunderland player:]
"I was as surprised as everybody else hearing the news this week.
"But the club has been in a downward spiral and Roy is somebody who can reverse their fortunes. What happened was a long time ago and they'll both have thought long and hard about whether they can work together and it will all have been worked out beforehand."