When they were deciding to make a movie about Alex Higgins, the makers soon realised a vital tenet of faith while adapting scripted drama from the real thing.
Thus, while they could easily have made a story just about Higgins, it was an even better story when they decided to make it about Higgins and Steve Davis.
Darkness and light. Night and day. And, aptly, black and white. A nemesis. A foil. All shadows are evidence of light. And all sportspeople must have… a rival. Because for every winner, there must be a loser. This is the unscripted magic of sport.
Unlike other rivals, real animus existed here.
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It is not always the case; so often, art seeks to fabricate, not imitate, life.
James Hunt and Niki Lauda are an example; in 'Rush', their relationship was re-drawn into what felt like a scarcely credible enmity; Bjorn Borg and John McEnroe were good friends and always have been; so too Jack Nicklaus and Arnold Palmer.
But with Davis and Higgins, there was a deep and meaningful contempt, far beyond the obvious differences in terms of style, themselves an indicator of the dichotomy between the duo.
They were not just tuxedoed gladiators upon the green baize; away from it their lives were played out in vehement contradiction to each other.
There was something far more fundamental at play than the familiar sporting trope of challenger versus titleholder, the unshakeable against the constantly shaking, underdog versus favourite and, in this particular case, the "People's Champion" versus the world champion.
There was also a sense that boiling within Higgins was a constantly churning pot of resentment at how, in a sport that he had originally transformed for the colour TV age of the 1970s, he was now being overhauled once more by a greedy successor in the Thatcherite free economy of the 1980s.
Their rivalry was not merely about the amount of balls potted or frames won but hinged on the very essence of their sport.
Higgins so often felt that the world owed him a living; addled by alcohol, he honestly believed that snooker did too.
Barry Hearn, then, as now, the supreme manager of the best talent around, was able to calculate Higgins' value but also his cost. And so he decided against adding Higgins to his 'Matchroom' stable, who went snooker loopy and earned reams of cash; Higgins just went loopy.
"Can Alex Higgins live without snooker?" he was once asked, after his 1986 head-butting of an official resulted in temporary expulsion.
He answered the hypothetical question with his own. "Can snooker live without Alex Higgins?"
The bare truth was that it could; in fact, it had done so for quite a few years before that 1986 interrogation and would do so for quite a years afterwards, too.
Poverty bookended the life and death of Alex Higgins; although sepia-tinted memories survived, his popularity, even amongst friends, dwindled the longer he lived.
In contrast, Davis became more popular the older he got; even in his later playing days, crowds urged him on, largely because he was no longer dominant and they were supporting a novelty: Steve Davis, underdog.
If anything, the rivalry between the players was no less grim than the battle that existed within Higgins himself, between the demons which plagued him, prompted by the mental anguish which, as long as the public indulged his wild and wicked ways, remained untreated.
Men wanted to be him and women wanted to bed him. But Higgins couldn't love. He didn't just hate Davis - he hated himself most of the time, too.
That's what made the rivalry so captivating; Higgins' anarchic ambiguity set against the metronomic machine Davis.
To beat him, it often seemed as if Higgins had to empty himself; it was all or nothing. He is often incorrectly compared to Ronnie O'Sullivan.
But O'Sullivan, a multiple world champion and one of the best three players who ever played the game, grew up admiring Davis, also within that top three.
He may have loved watching Higgins. But he wanted to be Davis. He wanted to entertain. But he also wanted to win. Higgins couldn't complete the circle.
Higgins was a genius but, as in life, his ability to apply himself consistently was fleeting. The need to satisfy an adoring public so often smothered the inconvenience of winning.
For such an inveterate gambler, it's a wonder he just didn't back Davis for most of the '80s instead of wallowing in slow horses (his bets were legendarily large and always losing ones) and dodging sleep with wild, endless nights.
"Davis sends spectators to sleep," said the man who never slept, in a rare appearance alongside his rival after an even rarer win. "Spectators have no point of contact. How can you relate to a robot? I'd rather have a drink with Idi Amin."
"That was because Idi Amin would buy him more drinks," was Davis's quick-witted response; confirming there was more to the Essex boy than he was willing to reveal. It's just he didn't need to.
They once shared a long-haul flight together; Davis was anxious but the pair shared a blissful few hours of engaging chat. And then the drink took hold. The other Alex appeared.
They first met in the mid-'70s, in Hearn's Matchroom club; "I'm going to steamroller that ginger c**t!" Higgins would storm out to the bar, berating the crowd - "You bunch of w**kers!" He would return, but lose, twice; the match and the heavy bet he'd wagered on himself.
It would become a common occurrence; they met 31 times in regulated play; Davis won 25 of them; their final match, in 1990, a drawn league game.
Their '83 UK final, featuring a comeback to rival that of any, should have marked a watershed; Higgins had briefly been in a mental hospital, his wife had left him.
But after going 7-0 down, Higgins responded stirringly and, notably, abandoned his reckless style; winning safety battles, defying Davis with dogged match play.
"We are f**king back!" he roared to the shuddering theatre. It could have sparked a revival but instead it spiralled a downfall.
But this was only a glimpse of what Higgins could have been. The demons, inevitably, returned.
Life, like sport, rarely serves up a cinematic ending.