Princesses Beatrice and Eugenie appear inseparable. During royal events the daughters of Prince Andrew, Duke of York, and Sarah Ferguson, Duchess of York the sisters are always spotted side-by-side, but what's Beatrice and Eugenie's relationship really like? Do they share clothes, do they bicker and argue, or do the sisters get along famously?
They may be known for their memorable outfits and even more unforgettable hats, but there is a lot more to this sisterly relationship. And as she prepares to marry Jack Brooksbank, Eugenie will need her big sister Beatrice more than ever.
From their special nickname for each other, to living together, this is what you need to know, and may not know, about Princess Beatrice and Princess Eugenie's relationship.
The sisters are only 21 months apart
Princess Beatrice and Eugenie are the daughters of The Queen's second son Prince Andrew, Duke of York, and his ex-wife Sarah Ferguson, Duchess of York. Beatrice, 30 (born 8 August 1988), is the eldest of the two sisters, Eugenie is 28 (born 23 March 1990).
They were roommates
Before Eugenie and her fiancé Jack Brooksbank moved to Ivy Cottage, a home within Kensington Palace, in April the sisters lived together in a four-bedroom apartment at St James's Palace.
It's believed Beatrice still lives in their apartment. Meanwhile it's been reported that Eugenie and Jack now live nearby Prince Harry and Duchess Meghan and the royal couples have become quite close.
They're perfect opposites
In 2008, just before her 18th birthday, Eugenie gave her first media interview to The Telegraph, where she explained how she and her sister have very different personalities, yet they're differences make them a closer pair.
"We get on fantastically well, perhaps because we do and think different things," the Princess said.
"I am definitely not as polite as Beatrice, I have to say. I tell it as it is. I am shyer at first. Like, at a party I will say to Beatrice as we go in, 'Oh, you go first.' But then, when we're actually in, I am much louder and she is far more polite and solicitous."
Bride-to-be Eugenie has also been quoted saying, "I do have an occasional temper - I sort of inherited my dad's short fuse."
They have very different fashion tastes
As well as different personalities, the royal sisters also have opposite tastes in style. According to Eugenie, she's a little more low-key, while older sister Beatrice is a fan of the glitz and the glam.
"Beatrice loves her glamorous dresses and her hair being curly or big - like Mummy's - and I hate volume. I like my hair to be sort of flat. I like just throwing on a pair of jeans and generally being more understated. She is more 'Let's do the glamour.' We're chalk and cheese," Eugenie said.
They sometimes fight and argue
"It's quite funny how, like most sisters, we sometimes fight about clothes. I always take her clothes back to school, for instance, which she hates. We had a screaming argument over a pair of Converse trainers that I took back, which she said were hers and I said were mine," Princess Eugenie told The Telegraph.
"And in the end I realised they were hers when I found mine behind the door. Like all sisters, we have silly arguments about unimportant stuff, but we do love each other to death."
They're both working girls
Unlike some of the royal family, Princess Beatrice and Eugenie don't do official royal work and therefore aren't paid by the taxpayer. Instead, the girls have real-life jobs just like the res of us!
Eugenie is a director at the contemporary art gallery Hauser & Wirth, while Beatrice has a job at US technology firm Afiniti as an outsourcing strategist.
The sisters lean on each other
Princess Eugenie and Beatrice have a close bond with each other and also their mother. The threesome even have a cute nickname for themselves, 'Tripod'.
"What can't I live without? My family. That sounds cheesy, but I really can't," Eugenie revealed to Harper's Bazaar in 2006.
"Especially my mum. I wouldn't be able to make tough decisions without her. And my sister."
"My mum always says that we're the only ones who know exactly what's going on in each other's lives."
After the media mocked Beatrice for the outfit she wore to Prince William and Duchess Catherine's wedding, Eugenie stepped in to support her sister.
"There was a horrible article that had been written about Beatrice and she got really upset," Eugenie told Vogue UK.
"We were just about to step out and she had a bit of a wobble and cried. I was looking after her. And then about an hour later, I had a wobble and started crying and Bea was there for me."
Beatrice will be Eugenie's maid of honour
Just as Duchess Catherine had her sister Pippa Middleton as her maid of honour when she married Prince William, Beatrice will play a similar role on her sister's wedding day.
Princess Eugenie admitted that she's "not stressed at all" about her upcoming nuptials despite the underlying pressure.
"It's nerve-racking because you want it to be perfect, but then you realise that you're going to be with the person you love forever and nothing else really matters," the ninth in line to the throne confessed to Vogue UK.
And her sister has nothing but praise for the bride-to-be.
"Euge is amazing. She's a very modern bride," Princess Beatrice revealed.