Jon Walters had every reason to feel sick on Friday.
As the news broke of Roy Keane's addition to the Martin O'Neill ticket, Walters' memory must have raced back three years to his fall-out with Keane when they were manager and captain respectively of Ipswich Town.
It had been a relationship built on trust until it started to break down over Walters' courtship with Stoke City before deteriorating completely when the Scouser picked up a stomach bug just before a League Cup game in Exeter.
It says much about Walters' state of anxiety that the striker-cum-winger decided "to take a picture of me puke" on his mobile phone and forward it to the club physio as evidence he wasn't pulling a fast one.
Whether Keane believed him or not is neither here nor there. Within a month, Walters was off to the Potteries and speaking candidly about the explosive nature of Keane's managerial style.
"It wouldn't surprise me if some players are terrified of him," said the Republic international in 2010. "In my case, his words went in one ear and out the other.
"You never know where you stand with him and that was the fear factor he brought in. I respected him as a player, but maybe he can't get his point across as a manager.
"There's a way of going about b******ing people. At Ipswich, it became personal a few times."
Damien Delaney, also a former Tractor Boy, was once late to arrive at Ipswich's training ground while Keane was manager there.
Interrupting his progress were members of the local constabulary, who pinned him for driving his Audi A5 sports car at 44mph in a 30mph zone.
After pleading guilty by post to his speeding charge, Delaney then brazenly tried to deflect the blame towards Keane in a letter of mitigation to the magistrates.
"The reason I was going too fast was because I was late for work," Delaney wrote. "I had an unreasonable boss at the time who would not accept lateness and would not have listened to me."
Whether Delaney is ever offered the opportunity to listen to Keane again is one sub-plot to this remarkable story.
Similarly, Anthony Stokes – banned from the Glass Spider nightclub by Keane during their Sunderland days – may be regretting telling journalists a month ago that "we all got a rollicking off Roy".
Perhaps Stokes, Delaney and Walters should have reacted with caution as Keane will now be O'Neill's assistant manager – a spectacular development for someone who has had such a volatile relationship with the FAI and so many Republic players.
Yet, painting Keane as the bad guy is a cop-out. Those who know him well swear blind by his inherent sense of decency – referring to the stories of his anonymous charity work and the motivational trips he makes to people suffering from serious illnesses, telling them to stay positive and never give up.
Giving up was never a Keane trait. His managerial career may have declined after its spectacular start, and the stories emanating out of Ipswich bore a close resemblance to the ones which followed his Sunderland reign.
Yet, for all the bad signings, tactical mistakes and shabby man-management, there are reasons to believe he can successfully learn under O'Neill's guidance.
"I have got five children and I think I am a better father to my fourth and fifth," said Keane in February last year. "I have learned to be a better husband too.
"I think my driving has improved the longer I have been driving and I think my management will improve the longer I stick at it."
Nearly a year and a half after that interview, Keane is back, older – and for everyone's sake – hopefully wiser.
"Playing under Roy Keane is easy," said the Ipswich and former Ireland striker Daryl Murphy. "If you work hard, he praises you. If you don't, you get criticised. He's a fairer man than people give him credit for."