Prince Harry's upcoming bombshell memoir has the short yet very telling title of Spare.
The title is a direct link to Harry's status as a second-born son, his place in the line of succession and references the phrase “the heir and the spare" - being the child or children behind the sibling destined to one day inherit a throne.
And across the royal families of Europe, there are many second-born 'spares' like Harry, whose royal paths are less clear than their older brothers or sisters.
However, at times, they've never been far from the headlines, just like Harry, and here we take a look at some of their most controversial moments...
Prince Carl Philip of Sweden
Although he is now classed as Sweden's 'spare', life didn't start out that way for Prince Carl Philip.
He was originally heir to the Swedish throne when he was born as he was the eldest son of King Carl XVI Gustaf and Queen Silvia.
However, when he was just seven months old, Sweden made a change to the Act of Succession and introduced absolute primogeniture. And this put his older sister Crown Princess Victoria ahead of him - and she is now the future Queen.
In 2010, he raised eyebrows when he started dating former glamour model and reality TV star Sofia Hellqvist. The pair married in 2015 despite some backlash and they now have three sons together.
However in 2019, Carl Philip, was told that his sons would be removed from the royal household.
The two children of first-born Princess Victoria were the only grandchildren of the Swedish King and Queen to keep their positions in the line of succession.
Prince Carl Philip and Sofia - who are often compared with the Duke and Duchess of Sussex - retained their official duties and continued their charity work.
The couple even appeared to welcome the move, writing that their children would enjoy "freer choices in life".
Prince Joachim of Denmark
The spare behind the heir to the Danish throne is Prince Joachim - the younger son of Queen Margrethe.
And last month, Joachim spoke of his shock and slammed a move by his mother to remove his four children's prince and princess titles.
The move affects his children from his first marriage Prince Nikolai, 23, and Prince Felix, 20, as well as Prince Henrik, 13, and 10-year-old Princess Athena - the children he shares with his current wife Princess Marie.
Instead, they will have to use titles of count or countess and be referred to as their excellencies from next year.
Speaking last month, he told Danish news organisation Ekstra Bladet : "We are all very sad. It's never fun to see your children being harmed. They themselves find themselves in a situation they do not understand."
His mother later released a statement, with the monarch admitting her decision "makes a big impression" - for which she apologised - but said it had been made as a "Queen, mother and grandmother".
The move will not affect the children of Margrethe's eldest son and heir to the throne Crown Prince Frederik, who has two sons and two daughters with his wife Crown Princess Mary.
Infanta Cristina of Spain
King Felipe of Spain has two older sisters Infanta Cristina and Infanta Elena, who were both 'spares' before he took the throne in 2014.
And Cristina saw her title as Duchess of Palma stripped in 2015 after her former husband Iñaki Urdangarin became embroiled in a scandal.
In 2017, Urdangarin was sentenced to six years and three months in prison for embezzlement and money laundering - although this was reduced to five years.
It also led to Cristina to be investigated for corruption - but she was acquitted of any charges.
The pair announced their separation at the beginning of this year and Cristina no longer carries out royal duties.
Princess Martha Louise of Norway
Princess Martha Louise is fourth in line to the Norwegian throne behind her younger brother Crown Prince Haakon and his children Princess Ingrid Alexandra and Prince Sverre Magnus.
She married her first husband Ari Behn and they had three daughters together before they divorced in 2017. He died in 2019 after taking his own life.
In 2019, Martha Louise revealed she was in a relationship with self-styled shaman Durek Verrett and teamed up with him for a series of workshops entitled 'The Princess and the Shaman'.
However, she was later forced to drop any references to her princess title when it came to her commercial work.
The couple later became engaged and her father King Harald congratulated them but later admitted there had been a "culture clash".
Princess Stephanie of Monaco
Princess Stephanie is the youngest child of Prince Rainier III and Princess Grace of Monaco, while her older brother is Prince Albert of Monaco.
She was in the car with her mother Grace when their vehicle lost control and careered down a steep road in Monaco in 1982. Both were taken to hospital where Grace sadly died. Stephanie suffered a hairline veterbrae fracture but later made a full recovery.
As an adult, Stephanie has been a model and singer and has had a colourful love life.
She married her former bodyguard Daniel Ducret and the couple had two children - Louis and Pauline - before they divorced.
She later had a third child called Camille, who recently revealed on Instagram her father is Jean Raymond Gottlieb, a former palace bodyguard.
In 1999, Stephanie struck up a relationship with elephant trainer Franco Knie after they met at Monaco’s annual International Circus Festival.
She moved into his circus caravan with him and her three children but she later returned to Monaco in 2002 after they split. She then married Portuguese acrobat Adans Lopez Peres in 2003 but they divorced by 2004.
