The relationship between the X Factor mentor and mentee was always a tricky one.
Each year a group of excited wannabe pop stars would pray they'd get paired with their person of choice.
Options included loveable Louis Walsh, Girls Aloud's Cheryl and the music tycoon himself, Simon Cowell.
The mentors were responsible for helping their protégé with their song choice and giving them the confidence to be the best that they could be on stage.
However the pairings weren't always harmonious.
Simon Cowell and Louis Tomlinson
It's no exaggeration to say Simon Cowell changed Louis Tomlinson's life.
The wide-eyed teen, now 30, shot to stardom after the music mogul, 62, lead put him in One Direction and led the boy band to Beatles-esque fandom.
Fresh from his stellar success, Louis came back on the show as a judge - but things weren't the same between him and Simon.
The pair had a blazing argument live on-air on the X Factor in 2018.
Louis clashed with his former mentor during a row over his hopeful Brendan Murray's song choice.
Praising Brendan, Louis said: "That was the perfect song for you. The perfect performance."
However Simon cut across him saying it was actually him who chose the song.
His feathers ruffled, Louis snapped: "I chose it actually Simon. You certainly didn't choose it."
However the father-of-one wasn't having any of it, clapping back: "I thought I chose it. You don’t remember me calling you suggesting that song?"
Louis fumed: "No Simon. No you certainly didn't."
Louis Walsh and Sam Callahan
Sam Callahan branded Louis Walsh 'useless' after he announced he was quitting the X Factor in 2018.
Louis, 69, was Sam's mentor when he took part in the ITV talent show in 2013.
Speaking to FUBAR Radio, the now 27-year-old said: "I didn't think he knew what he was talking about then.
"I'd rather have someone young and hungry and a bit more with the times, [rather] than someone who can tell me about their credentials, but probably can't keep up in this day and age."
In 2017, Sam told Mirror Online that Louis had no input in his performances, and said the former Westlife manager would just show up for 10 minutes to film VTs.
He said: "I have been known to say before, and I stick by this, that Louis Walsh, I don't believe had any input or any say in how far I went in the competition by mentoring me."
Sam then really put the boot in, claiming: "I don't believe any of the judges have anything to do with the artists in terms of mentoring throughout the competition."
Simon Cowell and Jamie Archer
Simon and his mentor Jamie were accused of having a blazing row in 2009.
The Syco founder apparently told the now 46-year-old to ditch his version of Elvis' 'If I Can Dream' at the last minute.
The pair were said to have had a 25-minute screaming match after Simon ordered Jamie to switch to U2's 'Angel Of Harlem'.
An X Factor insider told The Sun that Cowell shouted: "That was well below par. You are finished if you sing that.'
"You need to change your song and start learning the lyrics fast or you are not just going to let yourself down - but you'll let me down too.'
At one point Jamie accused his mentor of 'wrecking this for me', the insider said.
X Factor star Lucie Jones, whose mentor was Dannii Minogue, weighed in on the debate and said one of the reasons Simon had argued with Jamie was because he hadn't been there during the week.
She told News of the World: "Simon has a man who helps him with the acts during the week, then it gets to Friday and he'll see his acts and often not really like it.
"Jamie would find it difficult because Simon would change his song on the Friday and he'd be like, 'You haven't even been here'".
Cheryl and Cher Lloyd
These pint-sized pop stars were best pals after the then 16-year-old burst onto the stage with her rendition of Soulja Boy's Turn My Swag On.
Cheryl, 38, thought her protegee was 'right up her street' - but then things turned sour.
After making it through to the live shows, Cher, now 28, earned herself an unenviable moniker of 'most hated teen' in Britain after reports of backstage strops.
She then accused her mentor of relying on autotune when asked if she'd consider duetting with the mum-of-one.
Chezza wasn't pleased and clapped back on social media: "Be Careful who you kick on your way up .. They kick you twice as hard on your way back down.. #unappreciationisugly."
