Intense. A control freak. Powerful. Unapologetic. A leader. Emotional. A genius. Mikel Arteta is the man driving Arsenal's irresistible resurgence.
There were signs of what was to come during his playing career at the Emirates. 'He was unbelievably professional to the point where he was compulsive,' one of Arteta's former Arsenal team-mates tells Mail Sport.
'His preparation for every training session, let alone match, was meticulous. If anyone was going to become a manager, it was Mikel.'
Those obsessive traits are said to have got worse - or better, depending on how you look at it - since he embarked on a career in management.
Indeed, in the era of the head coach, Arteta is a throwback - a manager in the traditional sense. His fingerprints are all over this club, much like a certain Arsene Wenger.
To illustrate his all-encompassing reach, Arteta has been involved in discussions over how to improve the atmosphere at the Emirates and has been central to talks over the layout of the club's London Colney HQ.
Arteta has his own ideas on how the club should operate and his engagement on a range of matters significantly outweighs that of his rivals, who are far happier to delegate. But that's Arteta. All or nothing.
Arteta being Arteta, he would refuse to accept the lion's share of credit for shaping the modern Arsenal. And indeed the Spaniard has been ably assisted by the Kroenkes, sporting director Edu and executive team Richard Garlick, Tim Lewis and Vinai Venkatesham. But Arteta is the puppet master, with the kind of influence enjoyed by only a handful of managers across Europe. And on Tuesday night, Arteta and his team enjoyed a watershed moment on a night bursting with unbridled joy.
The shootout win over Porto represented way more than simply their passage into the Champions League quarter-finals. It symbolised their progress.
First came the FA Cup triumph of 2020. Then last season's second-placed finish and qualification for the Champions League. And now their place in the Champions League last eight for the first time in 14 years.
But it was not just the victory that resonated, it was the manner of it. In the face of substantial provocation from a streetwise Porto side, the north Londoners managed to find a way.
It was not pretty, or particularly dominant. But that didn't matter. They got over the line.
Arteta is moulding this Arsenal side in his own image. The talent is clear. A team beautifully balanced with technical ability, pace, power and drive.
Yet their fortitude also stands out. It is a heady concoction that threatens to fire Arsenal to an unprecedented season.
'Culture, culture, culture,' explained one source when asked about the secret of Arteta's success. He emboldens his players and staff to take responsibility. A culture of accountability. And he doesn't expect anything from those around him that he doesn't expect of himself.
Some conversations are uncomfortable. Arteta can be forthright. Many who have worked with the 41-year-old say his unwavering honesty could do with being toned down.
But the Spaniard's view is that if you can't be truthful with your family, then who can you be truthful with?
That is exactly how Arteta views his colleagues: as family.
'He isn't afraid to say what he feels and that can lead to difficult conversations,' says an insider. 'But everyone inside the four walls of the training ground are like family to him. It's not just about the squad of 25 players. It's everyone.'
Arteta has an unwavering confidence in his decision-making. His move to dump Aaron Ramsdale as his first-choice goalkeeper in favour of summer signing David Raya was pilloried. Arteta was hardly seeking vindication, but if he needed any, Raya's heroics in the shootout win over Porto was an 'I told you so' moment.
Ask those who have worked alongside Arteta and they will tell you that is his nature. He is decisive and unflinching.
For instance, following a run of one win in seven matches towards the end of 2023, Arteta sanctioned a warm-weather training camp in Dubai. The primary goal was for his squad to rest and recuperate following a brutal schedule that had left Arsenal's season on the brink of unravelling.
But there was another motive for Arteta. The Arsenal manager's decision to invite family members on the trip did not win universal approval. Arteta, though, spotted an opportunity.
By inviting loved ones to Dubai, not only would it allow his players to fully unwind but also give the families a chance to bond with each other - a move that is said to have enhanced the sense of togetherness he has been so keen to nurture.
The trip to the Middle East proved the catalyst for a breathtaking run of nine victories in 10 matches - Arsenal's only loss in that time being the 1-0 Champions League first-leg defeat in Porto.
There was a serenity at the club's London Colney HQ on Wednesday morning. And that calm will continue as the players are due to have the end of this week off before the majority of them report for international duty.
The previous two wins, over Brentford and Porto, are being viewed internally as their most crucial of the season so far. Nasty, gritty, ugly wins.
It is 18 days until Arsenal face Manchester City in the league. The Gunners' mood heading into that daunting clash at the Etihad would be very different if these two matches had not gone according to plan.
But as it happens, they will be preparing for their trip to Manchester as league leaders and Champions League quarter-finalists.
Just don't expect Arteta to be satisfied with that.