KEY POINTS:
The O'Brien boys are in town trying to win the Melbourne Cup.
You've got Danny, a $7 cab ride from the back of the Flemington track where today they'll run one of the world's greatest horse races, and Aidan from Tipperary.
As best they know, the pair are not even distantly related.
But they share a common heritage - Irish horsemanship.
When first met, Aidan O'Brien gives the impression he's almost angelic.
Those who know him closely - and they are probably few - tell you 80 per cent of him is pure steel.
The rest of him is granite.
That's befitting someone who was a champion amateur jockey, a career not for the faint hearted.
Aidan O'Brien this afternoon produces Mahler for the world famous Ballydoyle Stables, run by a genius in John Magnier.
He is no relation to the previous Ballydoyle O'Brien - Vincent - whose job he took, but his record, achieved with blinding speed, is just as good.
In just 12 seasons of training Aidan O'Brien has won every major European classic bar the French Derby.
He has produced the first three home in the Irish Derby twice, trained the mighty Rock Of Gibraltar to win a record seven group ones in a row, beat legendary American trainer Bob Baffert's record by producing 23 group one winners in a season and became only the second person to be champion trainer in the United Kingdom and Ireland in the same year, something he's on track to achieve again.
He is one of Ireland's favourite sons.
Journalist Martin Hannan wrote: "Utter a word of criticism of O'Brien in the famous McCarthy's Hotel in Fethard and you're liable to leave in a box."
Racing history is littered with examples of the marriage between the Irish and the horse.
Aidan O'Brien is happy to admit he prepares horses by getting into their heads.
He doesn't like the term the horse whisperer, but it fits. His trade is the physiological make-up of the thoroughbred.
There might be something significant in the fact that last year when he produced the Melbourne Cup topweight and one of the favourites, Yeats, Aidan O'Brien didn't bother travelling to Australia.
This year he brought down two horses, but tragically the better one, Scorpion, went amiss last week.
You get the impression O'Brien has a slight concern it might be a year too early for Mahler, only a 3-year-old by Northern Hemisphere standards, but don't hold your breath waiting for him to say that.
He demonstrated the unique way he prepares his horses last week when raceday rider, Australian jockey Steven Baster, arrived at Sandown.
Baster thought he was there to ride Mahler, but O'Brien put him in the back of the four-wheel drive with himself as they drove around the inside of the Sandown track, 20 metres behind Mahler as he got through his work.
O'Brien wanted Baster to hear his thoughts on the work pattern, rather than Baster gauge if for himself. It was perfectionism, not arrogance.
If Mahler, the $10 third favourite, is to win one of racing's greatest prizes late this afternoon he has to get past Danny O'Brien's Melbourne Cup $5.50 favourite Master O'Reilly.
Despite his rugged background, you can see how the quietly spoken, immaculately dressed Aidan O'Brien slides perfectly into the elitist British racing scene.
Danny O'Brien, despite degrees in law and economics, is much more the knockabout Aussie bloke.
He's got time for everyone and is enormously popular on the Australian racing scene.
What that masks is O'Brien's dedication to hard work.
"This is one industry where you just can't have success without hard work and persistence," he said yesterday.
"This is a long haul. The old line that overnight success takes 20 years is true in racing."
When he turned his back on law and commerce, Danny O'Brien had a broad vision of where he wanted to go in horse racing.
Yet he didn't even dare think about the Melbourne Cup.
"It's [the Cup] above and beyond what it's going to do for your business."
You won't get him to say it, but the publican's son has a sense this could be his year.
He became a father for the first time a few weeks ago and produced a 1-2 result in the lead-up Caulfield Cup with Master O'Reilly and Douro Valley.
Visitor Aidan O'Brien, similarly, has been dreaming of a Melbourne Cup to add to his already remarkable record.
O'Brien of the Australian variety recalls his distant cousin from a few years ago when he visited Ballydoyle when Australian jockey Damien Oliver was riding trackwork there.
"I doubt he'd [Aidan] even remember me, but I certainly remember him - he tipped me a stable winner at $10."
O'Brien D says he would like to repay that debt.
He just hopes it isn't at 5.00pm this afternoon.
