Why always Mario Balotelli? Truth is, no one seems to know

It was something his adoptive mother said to me that brought everything home. Silvia Balotelli was in Manchester, on one of her periodic stays, and it was after we had met and she, being a devout church-goer, had asked for a tour of Manchester Cathedral, that she talked about the infuriating difficulty of getting Mario to sit still for a moment. It was when she and he were alone that she could get through to him, she said, as on the night before when she'd virtually ordered him to watch a film on adopted children. And, like a child, he had obeyed.

No one but the diminutive, fairly frail Mrs Balotelli has ever managed to get through to the 22-year-old – sold to Milan for £17m rising to £19.5 with add-ons – who is a boy at heart. Not City manager Roberto Mancini; not City's player liaison team who have employed more ideas and strategies on him than anyone might reasonably expect; and not even his adoptive, multi-lingual sister Cristina, a distinguished journalist who in the early days tried to form a bridge for him to the ways of England. City's people will tell you that if only Mrs Balotelli had lived around the corner things might have been different, but her husband, older and more infirm than her, found the travel a huge challenge and the visits were intermittent.

It is not that Balotelli has lacked any type of intellect to grow into his surroundings. In his pre-City days, Cristina's efforts and entreaties had seen him be still for long enough to understand about child soldiers. A Brazilian refuge for destitute children and women in the Brazilian favelas, where he spent Christmas 2007 and 2008, was close to his heart and he loved a World Wildlife Fund summer camp at Sicily's Zingaro nature reserve.

But those were interests he could develop without the world crashing in. Balotelli is an individual who, dreading solitude, has always craved company – but only the right type. He needs those who appreciate his particular sense of fun, are not too deferential and who are on his wavelength. Mancini will tell you that it helped when his own son, Andrea, was on City's books, providing companionship from a compatriot of his own generation. But he left for Real Valladolid and Balotelli's best option was the accommodating but rather mature company of Patrick and Cheryl Vieira.

He was pushed back towards those who are the scourge of a wealthy club like City – those figures on the periphery who are full of promises of cheap gadgets and cheap sports cars and a good night out for young players – but are generally out to fleece them. Balotelli knew them all and they all generally cashed in. A worry at one stage was the sheer number of iPhones he was buying for the hangers-on – or "pimps" as one individual who the striker could trust describes them.

Those critics who are saying good riddance today will declare that a man has to grow up at 22, though it is hard to avoid the sense that the struggle to do so has its roots in his difficult start in life. Balotelli's adoptive status is an important part of him. Witness the video Mrs Balotelli was so determined he should watch in the ninth-floor flat he kept on Manchester's Deansgate. And though it is folly to attempt to analyse a man you have never had the chance of the most cursory interview with – his only full press appearance was a Sunday newspaper's group discussion, and he arrived so late that City's staff thought it was a no-show – it is hard to avoid the sense that he has not entirely escaped the formative years.

The surname "Balotelli" was legally denied him until 2008, such was the protracted nature of his wait to be legally adopted by the Balotellis from the couple of Ghanaian descent – Rose and Thomas Barwuah – who arrived in Italy when he was two but were unable to care for him adequately.

The relationship with his natural parents is cordial because he wants to maintain contact with his siblings – two girls and a boy – but he was under no illusion that the couple wanted to give him up. In the months before his adoption, nurses feared for the well-being of the child, who was born with an abnormal dilation of the colon, underwent a series of operations over two years and when out of hospital was found wandering the streets of Brescia, where the Barwuahs lived. In another world, he would have been considered in need of careful nurturing when finally taking his leave of the Balotellis, with their blend of firmness and affection. The family's fondness for Mancini – who brought compassion to their boy at Internazionale while Jose Mourinho had displayed open contempt – convinced them City would be ideal. But it is no ordinary world he occupies.

Ask Mancini about why he spent £24m and staked his own reputation on a player Mourinho considered "unmanageable" and he will go dewy-eyed and talk about the finale to the 2007-08 season, when young Balotelli scored four goals in six games for him, as Inter won the Scudetto. Those were the moments which led the City manager to tell us repeatedly that this player would be one of world's best, one day.

Mancini certainly gave it a good shot before accepting that Balotelli's maddening unpredictability was beyond him. The episodes will all be trotted out over the next few days – the firework, the dart, the trampoline he emerged from the Trafford Centre with when sent in by his mother to buy an ironing board. But it was the most recent of the many bust-ups which has demonstrably altered Mancini's words of wild optimism about his prodigy. After a Christmas in which Balotelli had simply lacked the fitness to be considered for a first-team place, Mancini pulled him aside before training on 3 January and said: "This is your chance in life. Don't waste it." Within 25 minutes, his striker was squaring up with him, having virtually assaulted Scott Sinclair with a challenge which forced the manager to intervene. Little wonder Mancini had his head in hands after he sent Balotelli away.

Behind the scenes, there have been gentle supplications to Balotelli from Mancini to go to Italy and see his baby daughter Pia, born to Raffaella Fico, who offered domestic security for a time and with whom he was happy. Balotelli never has. Mancini is baffled. In the end, it was the sheer uncertainties that wore him down.

For all of that, his departure did not seem likely a week ago. City had not gone looking for it. There is much he will miss about England. He loves its racial tolerance, something we never got the chance to discuss with him. And though he hated the headlines, he abhors the Italian showbiz press's obsessions with him much more. God knows how he will deal with the new torrents of attention which surround him but he will at least have his mother near. And she is probably the only one who can save him from himself.

Mad Mario: Balotelli's City career

Aug 2010 Arrives from Internazionale for £24m.

Nov 2010 Scores first league goals at West Bromwich Albion, before being sent off.

Dec 2010 Hits only City hat-trick in 4-0 win over Aston Villa.

Mar 2011 Reported to have thrown darts in the direction of a youth player at training. Sent off against Dinamo Kiev.

July 2011 Taken off by Roberto Mancini after trying to score with outrageous back-flick at LA Galaxy.

Oct 2011 Fireworks set off in his mansion in build-up to derby at United. He scores twice, celebrating by revealing T-shirt reading: "Why Always Me?"

Nov 2011 Receives third red card of City career, at Liverpool.

Dec 2011 Training-ground bust-up with Micah Richards.

Jan 2012 Given four-match ban for stamp on Spurs' Scott Parker, but not before scoring the winner.

Mar 2012 Interrupts press unveiling of new Inter coach Andrea Stramaccioni. Has on-pitch row with Aleksandr Kolarov over a free-kick.

Apr 2012 Sent off at Arsenal.

Jan 2013 Pictured having training-ground bust-up with Mancini.