The 28-year-old returned to her Irish routes, negotiating the 15 miles of winding country roads which led from Cork to her little home town of Cobh. The route was lined with well-wishers, the same people who cheered her when she came back from the 1993 World Championships with a silver medal, and the 1995 World Championships with a gold. The same people who felt for her when she returned, devastated, from the 1996 Atlanta Olympics and the following year's World Championships in Athens.
The flag-waving scene which greeted O'Sullivan as she emerged from the Lord Mayor's reception held in her honour at Cork's City Hall may have been a familiar one to her. But her appreciation of it was different this time.
"There were people of all ages there," she said. "Young children, grandmothers. It was unbelievable to see how much it meant to them," she said. "Because of the way things had gone for me in the previous two years, there was a stage when I was thinking `What does it matter if I run or not? What does it matter whether I win or not?'
"But I started to receive a lot of letters from people back home, and they were always encouraging me and praying for me. People I met in Ireland after the World Cross-Country were telling me how much of a buzz it had given them that I had won. It made a difference to them going into work the next day.
"When I was welcomed back in '93, '94, '95, I didn't really appreciate the supporters' feelings. The most important thing for me was, `got to run, got to run, got to run.' I definitely appreciate things more now."
For all that, the idea of involving running in her homecoming was one which instinctively appealed to her. "It was a good idea," she said. "It's so much easier to go out and do something you like doing. And at least it meant I'd have some control over what was happening."
The comment echoed her reaction in Marrakesh the weekend before last after she had beaten Britain's Paula Radcliffe to the eight-kilometre cross-country gold in the midday heat, and then added the four-kilometre title the following day - "I felt as if I was back in control again."
After two years of doubt, her world has fallen back together. The core of her being - Sonia O'Sullivan, champion runner - has been validated once more.
The intensity of her competitiveness - "It's as if I put blinkers on and nothing else exists" - has been evident from the day she earned a lollipop for winning an under-12s race at the Cobh Community Games.
It has made her comfortably off. The $80,000 (pounds 50,000) she received for her efforts in Marrakesh are the latest winnings in an eight-year career at the top level. She owns a flat in Teddington - where she lives near her manager and former coach, Kim McDonald, and trains with some of the leading Kenyan men - and a home in Philadelphia.
Her unusual single-mindedness became evident soon after she had taken up a US sports scholarship at Villanova University as a 17-year-old. She defied her coach and began to train herself - with outstanding results.
It is a quality which has worked both ways for her in her life, as she readily admits. "It is my greatest asset, and my worst liability," she said. The upside was demonstrated in 1993, when she was run out of the medals in the World Championship 3,000 metres by the astonishing emergence of the Chinese women, but recovered to split the Chinese in the 1500m a few days later to come away with silver.
All those instincts were at work at the Atlanta Olympics - the same, uncompromising attitude was evident. But while the spirit was willing, the flesh was weak. And such was O'Sullivan's nature that she had hidden the problem - as much to herself as anyone else - until it was agonisingly exposed on the track.
Irish sports fans can recall the details of that debacle with the clarity which English football supporters remember the penalty misses of Pearce, Waddle and Southgate.
Pale, glistening with sweat and way off the pace, she dropped out of the 5,000m final. A couple of days later she failed to qualify from the 1500m heats. Why? Nobody really knew.
O'Sullivan's failure to add to the Olympic golds already accrued by the Irish swimmer, Michelle Smith, became one of the most discussed topics in Ireland for a while.
As one Irish commentator wrote: "The theories market hasn't been so buoyant since JFK went to Dallas in a car and came back in a box."
It was said that she was unhappy in love. That her food had been tampered with. Even that she was pregnant. Eventually, medical tests indicated that she had been suffering from a debilitating urinary tract infection.
The next most popular question after "What went wrong with Sonia?" thus became "Why didn't Sonia go to the doctor?"
Her instinctive reaction after the 5,000m final - when she accompanied McDonald on a seven-mile run back to the house they were renting - said much about her attitude. There was something almost primitive about it - she seemed to be trying, literally, to run away from her problems.
"There were all kinds of articles in the Irish papers after Atlanta, particularly the tabloids," she said. "They were digging away - it was almost like a soap opera type thing.
"Most people decided to blame Kim for cracking the whip too hard in training. But the people who criticised him don't know him at all. He didn't know I was sick. How could he have known to stop?"
With hindsight, she accepts that she did herself no favours by her reluctance to seek medical advice, despite feeling distinctly unwell in some of her races before the Olympics. Even after the 5,000m final, she did no more than have a cursory word with the Irish team doctor, Joe Cummiskey, because, as she admitted, she did not want him to find anything wrong with her which would keep her out of the 1500m.
But she feels there was more than a simple, physical explanation for what happened to her in Atlanta.
"There was a lot of pressure on me, but I kept on denying everything," she said. "I kept pushing it to the back of my mind. I was really stressed out in the weeks before the Olympics - I just wasn't able to relax. I'm not the greatest talker in the world. But I would definitely do things differently now."
Her failure last year in Athens, she now believes, stemmed partly from the fact that she was trying too hard to make up for Atlanta.
"Every race I had was seen as being the Big Comeback," she said. "In the end I had to accept that there was nothing that could make up for Atlanta. It had happened and there was nothing I could do about it. I had to simply put it away."
The weight of guilt also appears to have dropped away. Shortly after her abortive Olympic 1500m heat, she said "You feel like a criminal when you lose like that." Now, you feel, she is free of the implied sentence - or at least, out on remand.
Her Marrakesh victory over Radcliffe, as she struck like a hunter with 600m to go, was in the old manner. In a word - controlled.
O'Sullivan believes now that the pain she has suffered in the last couple of years will work out to her ultimate advantage. "I think what happened to me in Atlanta and Athens will prolong my career," she said. "Because I think I've seen everything now, good and bad."
While preparing for the World Cross-Country Championships with a four- week stint of altitude training near Melbourne, she witnessed the way in which Australia was gripped by the ultimately unsuccessful efforts of its football team to qualify for the World Cup finals.
"It was a real let-down when they didn't make it," she said. "But when I saw the interest the team generated, I thought to myself, `maybe I could have this kind of effect in my country. Maybe I do.'"
And maybe she will continue to do so for many seasons to come. As for that old wilful streak - well, she maintains that for the past year she has diligently followed all instructions laid down by her new coach, Alan Storey.
"Everything he's said, I've done," she maintained - then chuckled as she recalled their little disagreement in Marrakesh over whether she should run the shorter race having won the longer one.
"Everybody was telling me not to run again," she said. "But in the end, I went with my gut feeling." When O'Sullivan's glittering running career finally does come to an end, somewhere beyond the Sydney Olympics of 2,000, that little phrase will probably sum it up quite well.Reuse content