Borussia Dortmund fans were really, really upset when rising star Mario Gotze decided to jump ship to Bayern Munich in 2013.
Having come through the academy and established himself as one of the rising stars of European football, Gotze felt the craving for silverware and left for his team's bitter rivals, thus ending any relationship he had with the supporters.
His return to Dortmund as a Bayern player was extremely hostile. The Dortmund fans made it perfectly clear how they felt about what had happened and effectively warned the players currently at the club what they could expect if they thought of doing similar, although it did not have the desired effect as Robert Lewandowski and Mats Hummels followed the same path.
But when Gotze had to warm up in the tunnel to avoid the wrath of the black and yellow fans, few saw reconciliation as a possibility.
He scored ten minutes after coming on, too.
But now the prodigal son is returning home. Borussia Dortmund will pay £22m for a player who left for their team to join the enemy as is returning with three consecutive league titles, two German cups, a UEFA Super Cup , and a FIFA Club World Cup to go along with the World Cup winning goal he managed for the national team.
And yet his time in Munich will be remembered as a disappointment.
He never found a role in the team under Guardiola, and has been mocked for his seemingly chubby physique having not really been given a chance to earn match fitness, but the first thing on Mario's mind as he heads back to BVB is repairing the damage.
In an official statement published on the club's site, Gotze apologised to the Dortmund fans and explained that if he could go back, he wouldn't have made the move in the first place.
When I switched from BVB to Bayern in 2013, that was a conscious decision that I will not hide from myself today.
Three years later, and with 24 years of age, I look with different eyes at my decision. I can understand why so many fans did not understand my decision.
Looking back at it, I wouldn’t do that again! When I return to my home, I want to try to please all people – especially those who did not receive me back with open arms – and to convince them with my performances. My aim is to play my best football again. For all of us, the club and the BVB fans.
It appears that he is aware that words won't cut it for the fans that turn up week in, week out, and that he needs to perform on the pitch. That's a good start.