Expats, exports, security: What's worrying the rest of the EU about Brexit?
As the leaders of the EU's remaining 27 member states prepare for the first Brexit summit in Brussels, which issues will shape the agendas of the individual countries taking part?
Germany: Jenny Hill, Berlin
Chancellor Angela Merkel is keen to emphasise that Brexit negotiations are between Britain and the EU but Germany's position will assume a significance above and beyond most - perhaps all - of the other member states.
This is partly because of its economic and political weight in the union but also because, unlike many other countries, it has the resources, the people and the expertise to analyse and work through the administrative complexities of deconstructing Britain's membership.
For a nation that considers itself to be European first, German second, the priority is now the future security of the EU.
Berlin wants to present a united European front in the negotiations, so it's likely to stick to a script agreed with the big EU institutions.
Expect a firm line too from Berlin on the rights of EU citizens living in Britain.
While there is concern in Berlin about the impact of what one German newspaper called "Britain's leap into the dark", and an acknowledgement of, in Mrs Merkel's words, the "enormity and complexity" of the negotiations ahead, but politicians in Berlin worry about the bigger picture too.
Mrs Merkel has made it clear all along that she wants to get on with tackling other challenges facing the union; migration, terrorism, youth unemployment, the impact of digitisation and so on.
And, she said on Thursday that, in a world of global challenges, Europe could not afford to be introspective now.
Berlin didn't want Britain to leave - but, now that the decision's made, it wants "fair and constructive" exit negotiations to be concluded quickly and cleanly.
But it's unlikely to support talks over the shape of the future relationship between the UK and the EU unless Britain first agrees the terms of its exit - ie commits to paying that "Brexit bill".
There is, in reality, little appetite here for a punitive approach.
Berlin wishes to preserve its strong economic relationship with the UK.
But don't expect Germany to be a soft negotiating partner either.
Even business leaders - among them the head of the association of Germany's all-powerful car manufacturers - acknowledge the EU's interests must come first.
Mrs Merkel has warned against the "illusion" the UK can retain or even negotiate better rights than member states.
In Angela Merkel's response to the triggering of Article 50 last month, she chose first to commit to minimising the personal impact of Brexit on EU citizens living in the UK.
And she is expected to seek to protect what she sees as those vital founding freedoms of the EU.
She has repeatedly insisted that there can be no access to the single market without freedom of movement of people - a red line upon which many will seek to compromise but upon which she is likely to stand firm.
France: Hugh Schofield, Paris
France is in the middle of presidential elections, and will have a new head of state in early May.
The two candidates have very different views of the European Union - and of Brexit.
If Marine Le Pen of the Front National is elected, all bets are off.
She is vehemently anti-EU, and thinks the UK's departure is not to be regretted but applauded.
With Ms Le Pen in the Elysee, the chaos created by Brexit would quickly be eclipsed as Brussels struggled to cope with a much greater threat - Frexit.
But realistically, Marine Le Pen's chances are small.
Far more probable is a President Emmanuel Macron.
Mr Macron is fervently pro-European.
In recent months, he has spoken out strongly about how the UK must not be allowed special treatment in its negotiations with Brussels.
Echoing the outgoing President Francois Hollande, he says favours to London would betray the spirit of the EU and encourage populism.
The obvious conclusion is that he would take a tough line in the talks on Brexit.
But another interpretation suggests he might actually make life easier for the UK's negotiators.
This is because on many issues Mr Macron is in agreement with the UK.
He is economically liberal, pro-trade and pro-business.
He understands the City.
Hope for this more favourable view comes from a policy paper co-written by Mr Macron's top adviser, Jean Pisani-Ferry.
In it, he argues for a "continental partnership" with the UK, in which London would have access to the single market (and pay into the EU budget) but win back control over movement of workers.
This is seen as a very soft version of Brexit.
Optimists say that a Macron victory would be seen as the start of a rollback against populism in Europe.
A more confident Brussels establishment would then be more likely to reach a generous deal with London.
Poland: Adam Easton, Warsaw
Poles make up the largest non-British nationality living in the UK, so the first priority for the Polish government is to secure the rights of those 850,000 Polish citizens.
It's thought that many of those Poles have not been living in Britain long enough to claim permanent residency, so there's a great deal of uncertainty among them about their future rights post-Brexit.
Warsaw wants to be seen to be protecting its citizens' current status, including their access to UK social benefits.
Essentially, it wants the current rules to remain in force.
Those workers' earnings are important for the Polish economy.
Each year, they send home an estimated $1bn (£780m).
Another pressing concern is securing the UK's contribution to the EU budget.
Poland is the biggest recipient of funds - 106bn euro (£90bn) under the 2014-20 EU budget, to which the UK is a significant contributor.
Those funds have transformed the infrastructure landscape of Poland, and helped drive the country's economic growth.
Warsaw hopes Brexit will not mean less money in the pot.
Before the referendum, Poland named Britain as its number one partner in the EU.
It insists the UK will remain a strong ally, especially in areas such as defence and Nato cooperation.
Russia's annexation of Crimea and the war in eastern Ukraine have increased concerns in Poland and the Baltic states about security.
British soldiers have been deployed to the region and are taking part in the defence of Nato's eastern flank, a contribution that Warsaw values.
Spain: James Badcock, Madrid
So often the rock of contention, Gibraltar looms large over the impending Brexit negotiations.
Spain lobbied hard to ensure that the British overseas territory was specifically mentioned in the European Council's draft guidance document, which states that Madrid can veto the application of an agreement between the EU and the UK to Gibraltar.
Since Spain joined the EU, Gibraltar has been able to call on Brussels to intervene when it felt Spain was squeezing traffic unreasonably at the land border, charges Madrid has consistently denied, citing security concerns.
Now, there will have to be an agreement between Britain and Spain to apply the eventual Brexit terms of trade and movement of people to and from the British overseas territory.
Spain has proposed joint sovereignty, something Gibraltarians - and UK governments - have traditionally rejected out of hand.
But aside from grandstanding on the Rock, Spain has many reasons to make Brexit as soft as possible.
The Spanish consulate in London says 130,000 Spaniards live in Britain.
On the other side, 309,000 British citizens are registered as residents in Spain.
Here, the two countries will seek reciprocity on a deal making migrants' lives comfortable.
Tourism is Spain's leading economic driver.
According to the Spanish government, 23% of the 75 million foreign tourists who visited the country in 2016 came from Britain.
There are strong financial links between the two countries too.
Spanish company Ferrovial operates Heathrow and several other UK airports.
Santander says 20% of its profits in 2016 came from its UK banking operations.
Spain consistently runs a healthy trade surplus with the UK.
Madrid has said it will work for an amicable deal with Britain, but the shadow of an impending row over applying it to Gibraltar threatens to be a major political stumbling block.
Italy: James Reynolds, Rome
Expats, exports, security - these will be Italy's three immediate Brexit negotiation priorities.
Italy's embassy in the UK estimates there could be up to 600,000 Italians living in the UK, while it is thought that only 30,000 Britons live in Italy.
Many of the Italians living in Britain are young graduates who cannot find work at home.
Italy will want to safeguard their rights - and find a way to ensure future graduates can continue to look for work in the UK.
Then, Italy will want to make sure that it is able to carry on selling its goods to the UK.
Britain is currently Italy's fourth biggest export market.
In 2015, Italy exported 22.5bn euro (£19bn) worth of goods to the UK including cars, machinery, clothes, and the sparkling wine prosecco.
Italy will also seek to maintain a security alliance with Britain, particularly in the Mediterranean.
As an EU member, Britain has taken part in anti-smuggling operations off the Italian coast.
Italy and the UK have also worked together in efforts to stabilise Libya.
Brexit also presents a number of opportunities for Italy.
The EU must decide the fate of its agencies currently based in the UK.
Milan is taking part in the unofficial competition to take over as the host of the European Banking Agency and the European Medicines Agency.
Sweden: Maddy Savage, Stockholm
It's never fun watching your best friend go through a break-up, and it gets a lot more complicated when you've got a bunch of friends in common.
That's the position Sweden finds itself in, as its closest ally prepares to divorce itself from the EU.
The two countries have shared the same perspective on 90% of votes in the European Council, and the UK is the Nordic nation's fifth biggest export partner.
Ever-efficient Sweden has made no secret of its desire for negotiations on a new trade agreement with the UK to start as soon as possible.
But its first priority is clarity on the future rights of EU citizens to live, work and study in a post-Brexit Britain.
According to the Swedish government, more than 100,000 Swedes, from a population of just 10 million, are based in the UK, and about 1,000 Swedish businesses operate there.
Sweden's Minister for European Affairs and Trade, Ann Linde, has been openly critical of the challenges facing Europeans seeking permanent residency in the UK under current rules, which include filling out an 85-page document and providing evidence of steady work.
While Sweden's centre-left government has said it wants to make sure its old friend gets a "fair deal" in the negotiations, it has made clear that keeping the rest of the 27-member bloc intact is its core goal, a message shared by the country's centre-right opposition parties.
But public support for the anti-immigration Sweden Democrats - who are pushing for a "Swexit"- has crept up to about 19%, with just over a year to go before the country's next general election.
Meanwhile, Sweden has seen a huge spike in citizenship applications from British expats anxious to guarantee their future in Scandinavia, with 1,616 forms submitted in 2016, three times the total of the previous year, 511.
The Netherlands: Anna Holligan, The Hague
A "self-inflicted wound" is how one bewildered Dutch columnist described Brexit.
The UK has historically been one of the Netherlands' closest allies.
Exports between the two run into the tens of billions of euros.
A comprehensive free trade agreement will be a priority - the Dutch government's biggest fear is having to fall back on the World Trade Organization tariffs.
But bear in mind, the Netherlands was one of the first recruits to the EU club of nations and about 80% of the country's GDP comes from exports, most of which (79%) are within Europe.
The strength of Britain's relationship with this small but influential ally could prove critical in determining the nature of the final deal.
In fact, the pragmatic Dutch could emerge as mediators.
They are the masters of compromise, proud of their ability to put differences aside to work together in the common interest, to literally dig the land out of the sea.
They have their people to think about too.
The Dutch foreign minister told the BBC that securing the rights of the approximately 100,000 Dutch citizens who lived in the UK was a top priority in the negotiations.
And the Britons based in the Netherlands are anxious to be afforded the same protections.
The domestic political landscape could also influence the Dutch stance.
Eurosceptic parties performed well in the recent election.
They were emboldened by Brexit, despite the fact support for a "Nexit" fell after Britain demonstrated the complications involved in extricating oneself from the EU.
The Dutch dilemma will be how to maintain the valuable economic, cultural and political links with the UK without bolstering the eurosceptics at home and across the continent who want to destroy their lucrative club.