Whatever is going on in Brad Shields' head now that he has been named to play for England against the All Blacks, may be scrambled to the point where he feels overwhelmed with emotion come game day.
Playing against the nation of his birth may test him in ways he hasn't imagined or more probably, can't fully understand.
Having previously coached Wales against New Zealand, All Blacks coach Steve Hansen is well placed to know how it feels to be on the other side of the fence as it were and suspects Shields will find the whole business more contrasting and difficult than he currently suspects.
Hansen is not sure whether former All Blacks coach John Mitchell, who is now in charge of England's defence, will necessarily find the experience to be as challenging as he did when it happened twice in 2003.
To some extent it is easier for coaches – particularly those in assistant or specialist roles – to distance themselves from the emotion of it all and convince themselves they are simply doing a job.
They are hired professionals, brought in for their expertise that is adapted to suit the team they are coaching.
There is no need to be emotionally invested – professionally committed and driven, but the heart doesn't need to be given over.
But Hansen is certain that Shields won't be able to protect himself from the mixed feelings he'll have at Twickenham.
It won't be so easy for him to pretend that a little piece of him isn't dying inside that he's wearing a white jersey instead of a black one.
The strangeness of seeing some of his closest friends in the other team, fulfilling the dream he too held for 27 years, will hit him hard – probably when the anthems are played and then again when the haka is performed.
"It wasn't that pleasant we used to get thumped," Hansen said on what the experience of coaching against the All Blacks was like.
"It is emotional. But in saying that John has been away from New Zealand for a long time so I don't know if he still harbours those emotions or not.
"For me it was pretty raw and I found it the other way, too. In 2004 I finished up in Wales and then came back again in November and we played against them. That was pretty emotional but I guess the closest to that is going to be Shields.
"He's going to be lining up facing the haka, facing the team that he's always wanted to play for. But unfortunately for his sake, we didn't pick him and now he's got the opportunity to play against us and some of his great mates are in this team so he will find it emotional I would say more so than Mitch."
Whether Hansen was deliberately trying to unsettle Shields is hard to tell. Possibly he was, while also making a point about his dissatisfaction with New Zealand players who give up on the black jersey and throw their lot in with other international sides.
Potentially it is hypocritical of a coach who left New Zealand to coach another country's test team to sit in judgement of players who do the same thing.
But the landscape is different for coaches. There are no eligibility rules or restrictions that mean once an individual has coached one country they can't coach another.
A mission to Wales can therefore legitimately be viewed as a means to advance a coaching career – to gain the critical international experience required to progress towards being the All Blacks coach.
An offshore venture for coaches is a means to build their portfolio and bring back to New Zealand a wider knowledge of rugby systems and ideas.
For players, there is no such luxury of being able to play test football for one country to further their case to win selection for another.
They get one choice and once they make it, there is no going back and Hansen is perhaps suggesting that the enormity of Shields' decision probably hasn't hit him yet.
He won his England call-up in June, suddenly and a little dramatically as it required special clearance to allow him to play.
The excitement of it all no doubt swept Shields along without any need to consider what he had said no to by saying yes to England.
But that moment of realisation is coming and it will be in Shields' face at Twickenham – the moment where he will have to confront the feelings inside him and challenge himself for the first time since he jumped ship, to truly question what is in his heart.
"You wouldn't be human if you didn't," says Hansen. "But he's a quality man and he's a good rugby player so he'll deal with it in his own way but it will tug at his heartstrings.
"Like I say, he wouldn't be human if it didn't."