Farrell's life is already one of precocious maturity. Virtually the finished product as a player from his early teens, he became both a father and a Wigan first-teamer at 16. At 21 he is the youngest captain to take Great Britain on tour - and not just any tour, either.
"In one sense it's been easy," said Farrell, to whom the formal side of the job, the speeches and receptions, might have held more fears than the rugby which has been second nature to him for as long as he can remember.
He need not have worried. Like the rest of the Lions party, Farrell has with him a blazer, shirt, tie and flannels that have not yet been worn. There have been no speeches, no receptions.
"I was expecting to have to do all sorts of things, but it's been a breeze. It's suited me in a way, because I've been able to concentrate on the rugby."
Lack of interest in the opposition at home and in New Zealand does have an effect, however. "Everyone out here has been putting everything into this tour and it just seems that we're the only ones bothered," he said.
"We are the ones who will take all the stick and the only thing we can do about that is to go out there on Friday and at least win our last match in New Zealand.
"We're desperate to do that. We've been written off and criticised back in England but we know we're better than that. The lads played really well in the first two Tests and they have deserved a lot better than they've got out here."
It would certainly be hard to fault Farrell's personal contribution, either on or off the field. His own form, even after 14 months continuous rugby in Britain, has been irreproachable, and even at his age he has the knack of putting players around him at their ease.
"Whatever has gone wrong on this tour, none of it is down to Faz," is the unanimous verdict of his peers.
"I felt sorry for Faz," said the tour coach, Phil Larder. "He's a very young captain and he's deserved better. He doesn't show anger very much but he was absolutely devastated when he heard that 11 lads were going home and he wasn't going to be able to see them."
Farrell has taken the role as the social catalyst for the tour very seriously. "You don't get to know players from other clubs during our domestic season, but on tour you strike up very strong friendships," he said.
"A tremendous bond builds up and when they take 11 of them away from you it's like a kick in the guts."
Farrell's job now is to get his team over that blow and the others dealt out by defeats in the first two Tests.
The cruellest irony will be if Farrell, the man who has had so much to do with holding it all together, had to sit out this last chance of salvaging anything. A side strain that has also restricted the movement in his leg has kept him from training so far this week, but Farrell is determined to be there at Lancaster Park on Friday.
His mood is that he must play, come what may. After that he can go home secure in the knowledge that he has done a difficult job, one not made easier by outside pressures, to the very best of his ability.
Everyone knew that Farrell could play like a man born to the job; he has also proved a distinguished leader, albeit in a doomed cause.
Some of it is in the blood. He comes from one of Wigan's famous rugby league families; his wife, Colleen, from another - the O'Loughlins. Their son, Owen, is just five and both Wigan and St Helens are talking, only half jokingly, about wanting to sign him.
There is little time to lose. If he follows in his dad's rapid footsteps, he should be ready for anything that the game can throw at him in a decade or so.
n The Great Britain Academy side, also touring New Zealand, beat Canterbury 44-14 in the last match before their third Test against the Junior Kiwis. Damian Munroe scored three tries and Matthew Salter two in a stormy match that saw four British players sent to the sin-bin.Reuse content