They live from different islands in the same country and together they have a ruthless winning series and life in coaching, Joe Schmidt and Steve Hansen have come across very different characters.
If he leads the world champions in his title defense, the Super All Blacks becomes the most successful coach of the modern era.
If he decides to step down and let someone else go, there are many in New Zealand who believe that Ireland's chief coach should be next.
They mostly worked in parallel universes as trainers, but since 2013 they have crossed tracks three times and their teams have engaged in quality epics.
Hansen is 2-1, but he knows his team was in the game every time.
He clearly respects Schmidt's work with Ireland and the appreciation has led his assistant Ian Foster to use his public appearance this week to try to get under the skin of the coach of Ireland.
Like the Lions tour when he and his local media lobbies on a grenade after a shell in Varen Gatland, Hansen is trying to react. Schmidt refused to engage.
He began several weeks ago when he suggested that Conor Murray would do a miraculous recovery for this week, a theory he doubled on Sunday.
When Ireland ruled Murray, Foster drew attention to Bundee Aki and Johnny Sekton. – The subject returned to Hansen, saying: "He loves to get what he wants."
Speaking before the end of the World Cup in 2015, Hansen presented his approach to his media work.
"In such an event, you know that you will have a lot of media commitments before you start," he said.
"You set your own way of thinking: let's have some fun with them.
"The key thing is that you want to get messages to people who support you, and that's your fans. You try to do as well as you can." I said at the beginning, enjoy the party. and hate it. Fuck him until you make him, then get out of here. "
From his many media engagements in his time as coach of Ireland it is clear that Schmidt does not share Hensen's enthusiasm.
"Personally, it's not something I'm dealing with," he asked the question about Hansen's playing of the games.
"I do not know whether it's playing, players like to get what they want on the pitch, some may be more louder than others. All Blacks' involvement with the judge last weekend was not different from other teams.
"For me, I'm too concerned about my players and my team and how to deal too much with what other people can say."
Schmidt's clumsiness over controversy and discomfort with media surveillance may be one of the things that throws him away with the idea of inheriting Hansen.
A recent documentary on world number one illuminated the decline in the private life of the trainer as he and his wife lifted the fence to stop interested viewers watching in his garden. For all of Schmidt's popularity here, it's not something he has to deal with.
As far as Hansen's influence on the field was concerned, Schmidt was excellent in his praise.
"His record is incredibly good, is not it? It's incredible," he said.
"Obviously he had a team at the top of the world rugby for nine years and it's an incredibly difficult thing.
"It can not be an era, which has to change from one era to another. When people like Rickey McCall and Dan Carter give up, others have to get in. But when you look at who entered, Kieran Read over the captain, Beauden Barrett – Worldwide player of the year 2 times – entered the offense as number 10.
"It's pretty hard to blame the quality of the players they have.
"I wish I went to Steve's trainings and meetings this week, but I was not invited."
Although he said that he did not have time to take everything that was said this week, Schmid certainly seemed aware of Foster's comments on Aku, who came for a lasting critique in his country because of his decision to move to Connacht and play for Ireland.
The coach of Ireland was ready with several local truths for the Kiwi audience.
"I think Bundee has fully demonstrated his commitment to the past year," said Schmidt.
"Everyone knows they will give 100 pc.
"It's As if I'm Asking", was Jerome Kaino 100% ready to play for All Blacks because he was born in a foreign country or Chris Masoe or Joe Rococo or any of these guys? So they trained all these guys, they were very ready to play for all the Negroes. "
So, Schmidt is sufficiently tuned even if he does not want to engage in verbal sparring.
All fields outside the field are important for field preparation, where Schmidt brings intensity and attention to the details of the party. On the contrary, Hansen gives an impression of a wider approach.
Certainly, he expects Schmidt to throw something in his own way.
"Joe is pretty good at finding a trick or two, so we'll expect one or two to come our way," he said.
Schmidt was skeptical about what he could do to surprise the world's best team.
"I suppose we'll find out on Saturday," he said.
"I'm not sure we've been collecting a lot of surprises, but you would definitely like to create some time and space somewhere because it looks like there's a massive, green rectangle there, but with 15 incredibly athletic, incredibly competitive men in the opposition, it's still hard to find a lot of space."
As always, he will let his team speak in the field.