When Virat Kohli gave his first press conference of the Australian summer ahead of the T20I series opener in Brisbane, the final question asked of him seemed a straightforward one. How do you define aggression? It was a half-volley almost, a friendly lob from a near-collegial Indian journalist to help Kohli contextualise the earlier talk of sledging and on-field confrontation that had dominated the press conference, and which have characterised his battles with Australia.

Kohli spoke of aggression with regards to how his team responds to the opposition if they feel a line of respect has been crossed, and more broadly about how it related to effort and body language. But the final definition he gave was the most notable. "For me," he said, "aggression is the passion for winning."

It has always been thus for Kohli, a man whose triumphant outbursts of joy have forever appeared underpinned by a pent-up, almost primal aggression. And when one considers that every action has an equal and opposite reaction, for the world's best batsman, that passion for success meets its match in a hatred of defeat.

There is a telling irony in the fact that many of Kohli's most celebrated batting accomplishments have come in a series or tournament in which he has been the vanquished. He has dominated Test series in Australia, England, and South Africa. He has been player of the tournament at the past two ICC World T20s. On every occasion, he has walked away a loser.

On the flipside, when India have basked in their greatest glories, Kohli has often been eclipsed as the headline act. In the 2011 World Cup, he was the team's fifth-highest run-scorer, while MS Dhoni's anchoring of the run chase in the final instantly earned him legend status. In famous home successes over South Africa and Australia (twice), he has not featured in his team's top three run-scorers. Of course, there are other series he can point to in which he has indisputably been the man, most notably during England's five-Test visit in 2016. But the point remains – amid all his achievements with the bat, Kohli is yet to find that legacy-defining pièce de résistance.

There is no World Cup final run chase. No groundbreaking Test series victory Down Under. For a man who strives obsessively to be the best, that absence must burn. But there is time. And imminent opportunity. *** Virat Kohli has never been understated. Not since he flipped the bird to the crowd at the SCG way back in 2012. And not when he mimed a 'mic drop' to celebrate his run-out of Joe Root at Edgbaston in August. But in Brisbane, something had changed. A couple of the more seasoned Indian journalists covering the press conference noticed it. Kohli spoke almost quietly into the microphone, as if he thought a softening of his tone might make the words carry less weight. They were carefully chosen, too. Gone was the aggression from four years ago; in its place, a considered approach that he doubtless hoped would lead to fewer headlines and subsequent distractions. Because when you're Virat Kohli, you have enough of those already.

Whether he likes it or not, Kohli's brilliance has made him a man apart, the most sought-after commodity in cricket and a global sporting phenomenon. He has spoken in the past about craving the anonymity that he once took for granted on the streets of Delhi, and the strangeness of fame. At the Gabba, he digressed just a little, and seemed more accepting of his fate. "I don't think anyone aims to be at the centre of everything," he said. "All the noise on the outside, it's as influencing as you want it to be. So I usually stay away from all of this. "I focus on what I need to do, which is work hard at practice, think where the team needs to head, and help my teammates as much as possible. "Those are my priorities; I don't really think of anything apart from that. All the other things are connected to the sport but my main focus is on the things I just mentioned." When he stepped out to bat the following evening, India required 93 from 70 balls.

Among the crowd of more than 30,000, there was a sense of expectation. One lady in the stands beyond long-on watched on with her adult daughter. Australians with Indian heritage, they quietly admitted they didn't have a particular interest in cricket, but the promise of seeing Virat Kohli in the flesh was enough to draw them in. The Indian skipper was out for four, but having seen him in the field and in the on-field post-match TV interviews, they left largely satisfied.

Not so Kohli. Defeat and a failure with the bat must have rankled the 30-year-old, because by the time he had touched down in Melbourne the next day, he had already requested a private net session in the bowels of the MCG. With three local net bowlers and a couple of support staff on hand, Kohli hit balls undistracted for an hour, refusing to call time until he truly was satisfied.

There were no photos or phones allowed. No other Indian players present. Away from the spotlight, this was the true Kohli, leaving no stone unturned in his meticulous preparation. The Melbourne weather forced him to wait an extra 48 hours to right the wrongs of Brisbane, but when the chance came in Sydney, he accepted it with alacrity. This time, he came to the middle with India needing 101 from 87 balls. The fierce focus was there from the outset. He pulled down firmly on his helmet grille with his gloved hand, and adjusted his box habitually. He looked around the field incessantly, making mental notes on the run. He berated himself whenever a ball didn't go exactly where it was intended.

With the run rate beginning to push towards the outer limits of achievable, he punched a four through point. Next ball, he advanced and hit the most sumptuous of off drives for six.

An over later he danced down the track again, this time flicking six more over midwicket. By the final over, India needed five to win. Kohli faced two dots, then hit a pair of fours to seal the deal. After the winning shot, he sprinted down the pitch, arms aloft, a beaming smile on his face. It was an unusual show of emotion, not just because the series was merely drawn and the business of the Border-Gavaskar Trophy was still to be played out; moreover, it was the smile that surprised.

Gone was the aggression. This was the grin of a man unshackled from the self-imposed burden of expectation. *** Four years ago, the Australians labelled Kohli a spoilt brat. They had some justification; Kohli had even used the word 'brat' at one stage to describe himself. Even at the time, he didn't disagree. "I said, 'maybe that's the way I am – I know you guys hate me and I like that'," he said after making a hundred in Melbourne. "I don't mind having a chat on the field and it worked in my favour.

I like playing against Australia because it's very hard for them to stay calm. I don't mind. I will give it on the field. It really excites me and brings the best out in me. They don't seem to be learning the lesson."

In the intervening years, it is Kohli who has been learning the lessons. In his final press conference in Mumbai before flying to Australia, he spoke about how his motivations had shifted from his more volatile days.

"When it comes to getting engaged in an argument on the field, or in a fight as people want to call it excitedly, I have been completely OK playing without an altercation," he said. "I am very happy within my own space. "On a personal level, I don't find the need to go and find these things anymore. I have enough belief in my ability, I can play without a reason to pump myself up. "Those were very immature things that I used to feed on in my early days of my career, so that I can get pumped."

Kohli has said his wife, Anushka Sharma, is to thank for the change in outlook. He once spoke about the cricketing pressure he placed on himself as a child – even when as young as eight – and the fact he regrets having locked himself inside a cricket bubble through his youth. But in recent years, he has evolved as a person, and Anushka is a recurring theme in that evolution. "I have realised a lot of things in the past few years since I've been with my wife," he said during an ESPN interview in May.

"Because she is a very spiritual person and I have sort of drifted on that path as well. Now things are unlocking in a way that is very difficult for me to explain to people. But I understand that I was always meant to do this. If I am meant to do this in every lifetime of mine, I will do it one hundred times over. It's a blessing."

It has also aided his development as a cricketer. In the four years since he last toured Australia for a Test series, Kohli has posted 35 international hundreds – that's 10 clear of his nearest rival, Australian Steve Smith, and at a superior innings-per-hundred rate. Kohli scored 692 runs across those four Tests in 2014-15 and became the first tourist in 86 years to hit four centuries in a series in Australia. According to his coach, Ravi Shastri, he has advanced as a player and a leader since.

"He's matured," Shastri said. "What you saw from him four years ago, he's played all around the globe since then, he's captained the side – that alone comes with a tag of responsibility, which has fit well on his shoulders, and he has adjusted extremely well. "He'll not take his foot off the gas, that's for sure."

The accolades only begin there. Legendary former West Indies captain Clive Lloyd said there would be room for Kohli in his all-conquering Test side of the 1980s, while Australia's Steve Waugh has told his son, Austin, that he should make the Indian his batting role model. Statistically, he is already the greatest-ever three-format batsman, though the disclaimer within that title means his contemporaries are his only rivals for the crown. But to be the best is apparently insufficient; he must win as well.

And Kohli's drive is obsessive, borne out in the manner in which he has not only transformed his mind, but his body, throughout his time at the top. His conversion into a fitness fanatic took place in the public eye, and soon enough he became a face for the fitness industry in India as well. Anushka, too, is renowned for her high-energy workouts, while the story goes that Kohli even spent an hour in the gym during their wedding day in Tuscany last December. During a 2017 interview with Star Sports, he talked about his fight to drop the weight that had dogged him in the early years of his career. "I didn't have great metabolism," he said. "I was very chubby when I was younger, my baby fat took a lot of time to leave me. Anything I ate had twice the effect on my body than anyone else.

And I understood after a while, it's hampering my game. "My mum thought I was anorexic, she started thinking I am on some fat burners or something, and I am not eating at all. It was very hard to convince her that this Punjabi (diet) is not something that's needed for my sport. "When I changed it, the first three months were torture … I felt like eating the bedsheets sometimes at night, because all I had next to me was roasted chana and water. "I would not touch anything. I knew that if I crossed these three months, the (rest of his life) was going to be wonderful." *** Approaching the summer, the wider narrative for India is of course their failure to win a Test series in Australia from 11 attempts, dating back to 1947. For Kohli, there is an opportunity to do what his predecessors – the deified Dhoni, Sachin Tendulkar, Kapil Dev and Sunil Gavaskar among them – have been unable to do. As central as Kohli clearly is to India's hopes, the extent of his influence and import in fact goes well beyond his deeds with the bat, or even his on-field leadership.

Indian captains have traditionally wielded significant power within the complicated world of the BCCI, and Kohli is no exception. The exit of former coach Anil Kumble, who had been handpicked by the Cricket Advisory Committee, made up of Sachin Tendulkar, Sourav Ganguly and VVS Laxman, is evidence of that. So it is Kohli, together with Shastri, who are largely responsible for filling the vacuum left by the absence of a 'director of cricket' type role, which encompasses matters far beyond what most international captains or coaches need to concern themselves with; think tour schedules, including India's much-discussed shortage of warm-up matches in South Africa and more recently Australia, and day-night Test matches, which the Indians are now the only full member country not to have played.

One recent piece in the Hindustan Times compared Kohli's influence within Indian cricket to that of Imran Khan with Pakistan during his lengthy reign as captain in the 1980s and 1990s. Continuing that theme, a landmark Test triumph in Australia – or victory at next year's World Cup – would be as much a success for Kohli as for India, in the same way Pakistan's 1992 World Cup win has become synonymous with the inspiration of Imran. It has taken Kohli years to win over India's older generation, with his brashness and willingness to engage in confrontation pushing against the rigid parameters of the country's past.

According to Indian cricket journalists of that vintage, there remains some resistance, but just as India the democracy is eager to move forward, so too are its cricket teams. Kohli was conspicuous in his support of the national women's side at the recent ICC Women's World T20 tournament, while his status as a confident, global presence has become representative of the bold new face India is showing to the world. And if Kohli can engineer an Indian Test series win in Australia, or a third World Cup triumph in 2019, he will surely receive universal adulation and ongoing support from his countrymen, no matter the generation.

In Australia however, it is a big 'if', even with the advantage of the hosts' two best batsmen being absent through suspension. A look back at India's most recent two Test tours here shows no bowler averaged 30 or below, while off-spinner Ravi Ashwin's combined average of 54.71 across six matches shows how a strength at home can quickly become a weakness abroad.

There are some indications Kohli will not be Robinson Crusoe with the bat. After a four-nil drubbing in 2011-12 in which he scored India's lone Test hundred, the 2014-15 series was a different story; Kohli's four hundreds were complemented by centuries to Murali Vijay, Ajinkya Rahane and KL Rahul, all of whom are in the current touring party. As ever though, the ICC's number one ranked batsman will be relied upon as India's mainstay and talisman, the player from whom his teammates draw confidence and belief.

After Kohli's match-winning knock in the final T20I in Sydney, opener Shikhar Dhawan stated as much. "We look up to him," Dhawan said simply. "We knew our game was in safe hands." Left-arm spinner Krunal Pandya followed the sentiment, neatly summing it up. "The self-belief was there," he said, "but having Virat in the middle is something different."