There is no single type of good deputy leader for a political leader but there is one type of bad deputy as Nikki Kaye and Todd Muller found out this week.
The bad deputy makes problems worse for the leader rather than better.
That's not to say Muller didn't author his own misfortune with his lack of preparation for big media events. Winging it might work for the first five seconds.
When right-wing media figures such as Mike Hosking and Mark Richardson expressed their disappointment at Muller's failures this week, it cannot be written off as the Press Gallery making mischief.
• Mike Hosking: Could Todd Muller have had a worse start?
• National leader Todd Muller slams three Labour MPs for 'abject failure' in government
• National leader Todd Muller defends his deputy leader Nikki Kaye over Māori heritage gaffe
• New National leader Todd Muller squares off against Prime Minister Jacinda Ardern for the first time
Muller's dream start was initially derailed by the fiasco over Māori representation on the front bench and Paul Goldsmith's whakapapa.
But Kaye, as well as Muller, has some lessons to learn from the past week.
She emerged from the leader's office with Todd Muller for his first corridor caucus run and instead of being the usual "nodding head" - when MPs stand slightly behind the leader giving a press conference - she piped up several times uninvited, and offered the Goldsmith nugget. He then backed up her claims.
It is not usually the way things work. It is meant to be the other way round.
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Kaye is unlike any deputy National has had in the past 20 years because she co-sponsored the coup against Simon Bridges as part of a joint ticket.
That has perhaps given her a greater sense of partnership in the leadership team than the traditional deputy.
Certainly she has a higher profile, and one of the most commonly asked questions of Todd Muller in the two days after the coup was why Kaye wasn't leader.
She had beaten Ardern twice in Auckland Central and had more years' experience in Parliament, they said.
Kaye will never be National Party leader because she is too left wing to be a bridge within the party in the way Muller can yet be.
She is a very intense, driven MP, some say obsessive, and has a legendary capacity to work hard on the issue at hand.
She also showed great strength in overcoming breast cancer when she was in John Key's Cabinet.
But within the party she is also a polarising figure because of her activism on socially liberal causes and that is more keenly felt now than ever because of the recent euthanasia and abortion debates.
There is a good reason Kaye has hung onto a seat that was a Labour stronghold for nearly 90 years. It's not just hard work and personality, but because many of her values align with theirs.
Most deputy leaders in National are not a natural fit with the leader, but have arrived in the job like an arranged marriage of convenience. That was the case from 2003 until now.
That was true of Bill English becoming deputy to John Key and Paula Bennett to Bridges.
Both English and Bennett had a small band of followers, not enough for them to win a leadership contest, but loyal enough to put their person into the No 2 spot for the price of a smooth transition.
Bennett brought enough support to keep Amy Adams out of the leadership in 2018.
Adams, who was strongly supported by Muller and Kaye at the time, has catapulted back to No 3, in what is almost a reversal of the 2018 contest.
The circumstances of Muller's leadership change, however, militated against a smooth transition.
The Muller camp's energy went into winning the vote, not the transition. And in the end, there is no way to completely prepare for the scrutiny that leadership brings, and the heightened expectation of performance that a coup brings.
Having enticed Adams out of retirement plans to be by his side as he announced the reshuffle was an important image to project, not of unity, but of competence.
If Muller is going to try to make that the key point of difference with Labour, having Adams and Judith Collins, the most competent of Key and English's ministers, so close is vital to the message.
Adams at No 3 is almost deputy, and with responsibility for Covid-19 policies is almost finance spokesperson.
But after all that has been said and done this week about whether Muller has a Māori on his frontbench, the issue is not going to affect the bounce he will give to the National Party. That is not in doubt.
Those people for whom it is a game-changer were probably never National supporters.
And if Muller had shifted Shane Reti from No 28 to say No 8, it would have been seen as tokenism.
The more important impact was Muller's failure to project a strong alternative to the Government's policies to respond to the Covid-19 economic crisis, and his failure to say whether National would spend more or less.
Muller might be easier to listen to than Bridges, he might be more "likeable", but he had nothing better to say this past week.
Muller is now attempting to get back some momentum. He made a fair fist of his appearance in a Business NZ webinar and even joked about one of his terrible interviews.
He released a small business policy in Auckland – a $10,000 grant for each new employee taken on after November – in what will be the first of policies he can claim ownership over.
Adams, Goldsmith and Collins were there in support, and he was in much need of a show of strength, as was Kaye - letting the leader lead.