Some things just fit hand in glove and once the notion of Roy Keane glowering on the sideline at Parkhead was floated, it was all but impossible not to think of it as somehow fated; something that will one day seem as natural and predestined as Keane wearing the red shirt of Manchester United.

Scan the list of the men who have been charged with enhancing Celtic's ongoing romance with its own history and authenticity and a pattern soon emerges. Neil Lennon, Martin O'Neill, Kenny Dalglish, Billy McNeill, Jock Stein, Gordon Strachan – all of them invested their souls in the game. They lived those Saturday afternoons in the merchant city and it's easy to place Keane in their company.

Roy Keane has rarely been quizzed on his religious faith but he must have the feeling that someone up there derives a cosmic amusement from landing him in these highly dramatic situations. Ireland or Celtic? It's Keane's decision but everyone has an opinion and Roddy Doyle's life just got more complicated.

Nothing meaningful has happened since Martin O’Neill brought Keane back into FAI circles by inviting him to join him as assistant manager. It was a bold and original choice and at the time to rescued Keane from a kind of managerial purgatory. After his unhappy tenure at Ipswich, there came the mystifying sense that the captains and controllers of British football had made their mind up on Keane. The market went cold on him, ignoring his playing career as the most influential footballer in the Premier League’s first decade and what was a stunning debut season in management when he led Sunderland from the base of the Championship table to promotion.

Small talk

There must have been a few months when Keane wondered if he would be forced to spend his post-football life doing the very thing that his younger self held in contempt, suited up and making small talk in the television studios on big European football nights. At the game but not quite in it. The couple of seasons Keane spent ostracised from the game said everything about the herd thinking and crippling caution which dictates managerial appointments and almost nothing about his potential. O’Neill did Keane a huge turn by giving him a chance to lace up boots and work with footballers again.

But O’Neill is sharp. Keane made sense. Ireland’s greatest ever and most decorated footballer, smart, energetic, eager to be involved and probably decent company during the long-hours-to-kill lulls which characterise international football.

O'Neill sounded resigned when he spoke about Keane and Celtic, noting that the official protocol had been observed, with Dermot Desmond putting through a call to ask his permission to speak with his assistant manager. O'Neill's circumspect reply when asked if Keane would travel on Ireland's forthcoming US trip makes it seem that if Celtic are to offer Keane the manager's job it will happen very soon.

Could he turn down the chance to lead one of the most famous and storied football clubs? Rangers' absence from the Scottish Premiership means Celtic will be heavy favourites to retain their title next year. Should they manage the tricky qualifiers route, it would give Keane a chance to pit his wits in the Champions League next season, an irony that won't be lost on former United supremo Alex Ferguson as he sees his old team consigned to a winter without elite continental games at Old Trafford. Keane would be a dream appointment for Celtic's significant Irish fan base, who have always regarded the club in a proprietorial way. Like many Irish kids, Keane himself was a Celtic fan. It all seems too perfect.

Perhaps the main reason for turning down the offer is the thought of encountering the seasons of dark, hate-filled energy which Neil Lennon had to endure while at Celtic. The Portadown man was adored at Parkhead but attracted a level of vitriol and abuse and genuine threats that would have shattered the willpower of many.

After Lennon left Celtic, the Observer published a piece by Kevin McKenna, the former deputy editor of the Herald and executive editor of the Daily Mail in Scotland. He argued that the treatment which Lennon suffered in Scottish football grounds and on the streets was a source of shame to all Scotland. Even the barest sketch of the backdrop to Lennon's time managing Celtic suggests a life of incredible strain: attacked by a fan at Hearts, attacked outside a wine bar in Glasgow, bullets in the post, a parcel bomb sent to his house, round-the-clock police protection for his family. Then the ritual abusive chants every Saturday.

Singled out

“Let none be in any doubt about this: Lennon was hated for his religion and country of origin,” McKenna wrote.

He was also singled out because he was a totemic and provocative figure in his playing days for Celtic and opposition fans associated him with everything they hated about the Glasgow club.

Keane, too, is a former Celtic player but his period with the club was brief and curiously uneventful. It could be that his presence at Parkhead would incite nothing like the same chorus of hate and anti-Irish passion which the mere sight of Lennon stoked up. But Keane is Irish. He is also a huge figure in world football. And he gets involved. He lives it.

The relentless devotion of Celtic fans and the uncompromising loyalty and factions within Scottish football holds much of what Keane has always wanted out of football. It is the antithesis of the corporate game.

Rangers are continuing their slow crawl from the brink of extinction and although gravely weakened by the staggering financial mismanagement, their eventual return to the SPL will be a huge moment, celebrated as fiercely as any of their 54 league titles. The past two years have been a bonanza for Celtic, strolling to titles while their rivals are on their knees. But it is a false scenario and deep down, they know that without Rangers, there isn’t as much point to Celtic.

So it is a big moment for Keane. You can bet that part of him will be reluctant to shake hands with O’Neill. It was easy to see that Keane has enjoyed the past six months and he is invested in this squad now and in what they are trying to do. Maybe O’Neill, who knows the mechanics of Celtic Football Club can negotiate a way for Keane to divide his time between Celtic and the Irish team.

But that’s just wishful thinking. The club game is 24/7. That’s what they all say. Keane spent his playing years watching Brian Clough and Alex Ferguson. He saw what they put it into, what it took out of them.

If he goes, and go he surely must, then it will be the Bhoys all the way.

Cos the song hasn't changed: Roy's keen, oh- oh Roy's keen . . .