PARIS (AFP) - Ms Segolene Royal's appointment to a new French government is the latest chapter in an extraordinary saga entwining affairs of state with affairs of the heart.

Ms Royal, 60, is the ex-partner of President Francois Hollande and the mother of his four children.

She is also a longstanding heavyweight figure in the Socialist Party, for whom she fought, unsuccessfully, the 2007 presidential election.

But when Mr Hollande named his first Cabinet in 2012, there was never any question of a place being found for the tall and telegenic army officer's daughter who is one of the party's best-known faces.

The reason?

The hostility of the president's then-girlfriend Valerie Trierweiler, the feisty and glamorous Paris Match journalist for whom Mr Hollande left Ms Royal.

Mr Hollande and Ms Royal's relationship, which began as student sweethearts, was officially ended after her election defeat by Mr Nicolas Sarkozy.

It has subsequently emerged that Mr Hollande and Ms Trierweiler were actually a couple well before then, and their illicit affair had become an open secret in the political world that was kept hidden from voters for the sake of Ms Royal's election hopes.

As the woman scorned, Ms Royal should have been the one to give vent to her fury.

Instead, she quickly re-established amicable relations with the man she met and fell in love with at the elite Ecole Nationale de l'Administration (ENA), the famed finishing school for France's would-be leaders.

In 2011, after her own bid for a second tilt at the presidency flopped in the Socialists' primary, she threw her weight behind Mr Hollande's successful campaign for the party nomination and helped him claim the ultimate prize a year later.

According to insiders at the Elysee Palace, Mr Hollande and Ms Royal's restored relationship made Ms Trierweiler intensely insecure and ferociously jealous.

It was a volatile cocktail that exploded within weeks of Mr Hollande moving in to the Elysee.

Ms Trierweiler fired off a tempestuous tweet expressing her support for an independent Socialist candidate fighting Ms Royal for a parliamentary seat she had been parachuted into by the party hierarchy with Mr Hollande's blessing.

The tweet was quickly deleted but not the damage.

Ms Royal lost the election and Mr Hollande publicly rebuked Ms Trierweiler over an episode that transformed the president's messy love life into a legitimate area of inquiry for the mainstream media.

Ms Royal generally kept her counsel but did famously let slip the observation that, "it is not Francois' last girlfriend she (Trierweiler) should be worried about, it is the next one".

The acidic barb was to prove prescient.

In January, glossy magazine Closer revealed that Mr Hollande was scootering about Paris in the dead of night for trysts with Julie Gayet, an actress 18 years his junior.

Ms Trierweiler swooned off to hospital with nervous exhaustion but was unable to prevent the inevitable.

The relationship was guillotined on Jan 25 and Ms Royal's path back to government was clear.

A regular on television, Ms Royal is fond of the limelight.

She recently graced Le Parisien magazine draped in nothing but a sheet while clutching the French flag in a recreation of Delacroix's painting Liberty Leading The People.

Asked recently if she had considered quitting public life, Ms Royal replied: "Never. After 30 years in politics, that would be unthinkable."

The cover of her most recent book shows her laughing, mouth open and head tilted back.

In it she refers to the knocks she has taken in her private and political life and her capacity to "stick a plaster over the wounds and start again".

She returns to government in the deeply serious role of environment minister.

But it is unlikely that her ability to reduce greenhouse gases will attract anything like the interest there will be in the intriguing personal dynamic created by her presence at Mr Hollande's top table.

During her time on the sidelines, Ms Royal was not shy about criticising the lacklustre performance of the government.

What happens if she breaks ranks from inside the Cabinet?

Will Mr Hollande dare to crack the whip?

When the family all get together, will they have a "no government business at the table" rule?

If the sales of glossy gossip magazines are anything to go by, a nation that once prided itself on sophisticated indifference to the sexual antics of its leaders, has, of late, become quite keen on tales of bed-hopping and back-stabbing at the top of the state.

Will love blossom anew now that the erstwhile couple are in the kind of roles they dreamt of when they first met?

After his fling with the much younger Gayet, will Mr Hollande find himself drawn back to a woman of his own generation with whom he has so much common history?

Ms Royal's return ensures the soap opera will run and run.