Rishi Sunak: Northern Ireland issues to test new PM
It is a given that political leaders come and go, but never have prime ministers regenerated quite so rapidly.
recent parallels between Downing Street and Doctor Who do not end there.
Like the show, which on Sunday brought back David Tennant as the charismatic Time Lord, in politics there is now talk of Julian Smith returning as Northern Ireland Secretary.
Whether that is just wishful thinking, or an actual possibility, is up to Rishi Sunak.
He was a vocal supporter of the former chancellor, who now has the biggest role in UK politics, having lost out to Liz Truss after his first audition to Tory members.
And given the new prime minister has to oversee a looming deadline in Northern Ireland this week, who he sends there will be important.
urrent Northern Ireland Secretary Chris Heaton-Harris is not exactly a fan of Rishi Sunak. 
He was intimately involved in the campaign for a Boris Johnson comeback, despite being one of many cabinet ministers who had urged him to resign in the summer.
On Monday, Mr Heaton-Harris changed his stance, pledging to back Mr Sunak.
Convention goes that he could be sacked as Mr Sunak chooses his cabinet, unless he opts to retain some Johnson supporters, which is not impossible, given there is absolutely nothing conventional about politics at the moment.
re is the endorsement Team Sunak received from Northern Ireland minister Steve Baker on Sunday. 
In a significant step, the outspoken Brexiteer - who previously backed Liz Truss - said Mr Sunak was the right candidate to solve the Northern Ireland Protocol dispute and unite the Tory party.
It is possible Mr Baker's support could land him a promotion to the top job in the Northern Ireland Office.
Or it could even end up going to another MP unknown to most here before landing in Belfast, which would mean a fourth NI Secretary in four months. 
Ultimately, whoever is in the job by this Friday, 28 October, will have a call to make. 
Do they push ahead with what Mr Heaton-Harris vowed: that if, by 00:01 BST on Friday, an executive at Stormont has not reformed, a date for another assembly election will be set?
Or, does the new Sunak administration change tack and introduce last-minute legislation to delay the deadline?
Or, does it push back any talk of polls for several weeks, given that there is a 12-week period built into the current law in which to hold a fresh election?
None of the political parties at Stormont are in favour of another election and instead hope a reset at Westminster could prevent a pre-Christmas poll.
ugh given the chaos still consuming Westminster, we cannot quite rule out a general election happening sooner than is scheduled in two years' time.
Election or no election yet, the Northern Ireland Protocol remains an issue that neither of Mr Sunak's predecessors managed to sort out.
While he did vote for Brexit in the 2016 referendum, the new PM was not initially in favour of the controversial NI Protocol bill - legislation that sought to scrap large parts of the original deal.
Introduced by Liz Truss to parliament during her brief stint as foreign secretary and currently being scrutinised in the Lords, can those still backing it be sure of its future under a new government? 
re is also the question of how Mr Sunak will be received by the DUP, which privately backed his rival in the last leadership race and expressed concerns about how he would manage the protocol dispute. 
Meanwhile, Sinn Féin has in recent days argued that the British and Irish governments will have to consider joint authority, if devolution remains mothballed.
Rishi Sunak only made his first visit to Northern Ireland in the summer, attending the Tory leadership hustings at a hotel outside Belfast.
While he spoke briefly about wanting to renegotiate the protocol, there was zero detail during a half-hour Q&A and he has yet to be tested on virtually all policies relating to Northern Ireland.
re are also questions for him as to when exactly households in Northern Ireland will get access to the £400 energy bills discount, which were promised by Liz Truss and Boris Johnson's respective administrations.
Few expect Northern Ireland to rank highly on the new government's agenda, but, just days into being, it will have some big decisions to make about this place.
No longer the understudy, how Rishi Sunak handles Northern Ireland will play a part in how the biggest performance of his political career is eventually rated.