Aside from family and closest friends, few have been able to earn either the enduring trust and faith of Roy Keane, never mind acquire the emotional empathy required to calm a career so often interrupted by great tumult. Apart from one man, perhaps.
His name was Michael Kennedy and, in many ways, his death yesterday reminds us that he could claim that he was so close to the former Ireland international soccer great that his status as a cherished confidante almost rendered him a member of the extended Keane clan.
On a weekend when Keane reminded us of both that volcanic anger, in his condemnation of his under-firing erstwhile employers at Manchester United, and also his deep distrust of so many, it is fitting to recall Kennedy's unique relationship with one of Ireland's truly global sport stars.
And also to assess how that, even if Keane often struggled to reconcile so many conflicts in his life, the man to whom he bequeathed so much trust was able to do so quite liberally.
Wasn't he, after all, also the man who played the same role as 'consiglieri' for Niall Quinn, castigated as the "Mother Teresa" figure during the greatest conflagration of Keane's career?
As Saipan erupted, Quinn would know that the best way of mending fences with Keane was to talk to their part-time solicitor, not their full-time manager.
And yet Kennedy managed to forge that delicate, so subtle path to guide both men on a shared path of experience even at times when each of them might have been more willing to metaphorically grab the other by the throat. He would eventually reconcile the pair.
Given the Corkman's legendary caution, it was no surprise that Kennedy had to earn Keane's trust, even at an early stage in their fledgling relationship.
When Kenny Dalglish and Alex Ferguson were vying for the then Notts Forest midfielder in the summer of 1993, Keane decided to engage representation via the PFA, despite being given Kennedy's name by his Ireland team-mate David O'Leary.
Soon, he would discover that the man he initially rebuffed was an even safer one.
Born in Highgate, north London to Munster parents (his father from Inch, Kerry and mother from Bandon, Cork), Kennedy's sporting passion was for football - and Arsenal.
His meeting with O'Leary, soon after his full debut for the Gunners, was accidental, introduced to the Dubliner by an Irish accountant called Tony Beatty. It would also be fateful.
He helped him buy his first house and forged a professional, then personal, relationship, thereafter. Later, he became a godfather to one of O'Leary's daughters.
Many more, including Frank Stapleton, Pat Jennings, Ray Wilkins, Brian Kidd, Kevin Moran, Denis Irwin, Shay Given, Michael Thomas, Steve Staunton, David Connolly, Ian Harte and Stephen McPhail, would benefit from the infinite wisdom of the media-shy partner in Herbert Reeves & Co.
After being helped with the move to United - and a few extra zeroes thrown in which demonstrated Kennedy's prowess - Keane relented and warmed to the new stranger in his life.
The friendship would become stronger with each passing year, enduring long beyond the time when the other major bond in his life, Alex Ferguson, had been consigned to history.
"With Michael," Keane said once, "I was totally secure, knowing that his sole concern was what was best for my football. Money mattered to me, but was not the number-one priority. For Michael, money didn't count at all. He was a football fan."
But he dealt in more than football. When his famous client ended up in a police cell days before the 1999 FA Cup final, Kennedy phoned Ferguson to smooth troubled waters.
Kennedy could also be a tough nut and his firm negotiations with the Old Trafford hierarchy would ensure that, as the 21st century dawned, Keane would enter it as the best paid player in the history of British football.
Even when Keane fell out with Ferguson, Kennedy did not; indeed, he attempted to remedy the situation as he had tried to do before the 2002 World Cup.
In that broiling Saipan torment, after Keane's wife Theresa, Kennedy was the first port of call in the storm for the fulminating Irishman; only then would he ring Ferguson.
Through it all, Kennedy never pressed advice on his most famous client - merely reminding him of the consequences of leaving the World Cup. It was Kennedy who made the final phone calls to the FAI's John Delaney and, ironically, his other client, Niall Quinn, to officially declare that Keane would play no part in the 2002 World Cup.
From that summer on, even then, it seemed the second coming of Keane the international player was being plotted; for Kennedy, tact was always his calling card.
Brian Kerr's attempts to woo Keane back were at all times assuaged by the calm considerations of Kennedy, who was able to acquiesce in smoothing the path to Old Trafford and a club manager who was extremely reluctant to allow his prize asset to return to the international game.
He was indeed a secret agent non pareil. If Kennedy could not staunch the bleeding in 2002, he at least helped close the wound four years later, when Keane and Quinn remarkably joined forces at Sunderland.
It was Kennedy who helped to get the pair in Sean Mulryan's house in Kildare before the chief executive, Quinn, invited his one-time nemesis to become manager at the club then bank-rolled by Irish investors, two of whom were advised by Kennedy.
The pair would, however, reunite and achieve moderate success with the sleepy north-east giant.
Later, there would be détente with Mick McCarthy, too, a private meeting before a public handshake as they met in managerial combat.
And then, of course, the greatest reunion, when Keane linked up with Martin O'Neill in an Irish management team which would see him stand for his country's anthem at a major international tournament in 2016, finally at one with the country he had once divided.
And through it all, Kennedy remained at hand with his steadying sense of good grace and acute intelligence.
Remarkably, he consistently demurred payment in an official manner from any of his famous clients, insisting merely upon a flat fee and only occasionally asking for match tickets.
His passing leaves so many players acknowledging the debts that are owed to Michael Kennedy.
That he didn't require payment for them is the simplest way to sum up his legacy.