It was two years ago, but it seems like a lifetime. Then, in April 2011, an 18-year-old Mario Götze scored a crucial equaliser against Hannover 96 as Borussia Dortmund closed in on their first Bundesliga title for nine years. But instead of sprinting towards the "Yellow Wall" to lap up the home fans' adulation he revealed a shirt with the name "Dede" on it and ran towards the team's veteran Brazilian, who was warming up near the touchline.

It was a tribute from the squad's youngest player to its oldest, a player who had served Dortmund for 13 years but was leaving at the end of the season. After the match, which Dortmund won 4-1, Dede was asked about his team-mate's display of affection, but he could not answer. His eyes went moist, there were a few quiet sobs and then he left, having said not a word.

For the Dortmund fans it was a moment to cherish – a wonderful young player coming through the ranks paying tribute to an outgoing legend – and Götze, more than anyone else, came to embody Die Schwarzgelben's renaissance.

That is why, when the news of his move to Bayern Munich filtered through on the night of 22 April, it hurt so much. This was not just any player leaving, this was the heartbeat of the team, the future of not only Dortmund but also the national team or, as Franz Beckenbauer had described Götze, "the Lionel Messi of Germany".

That he was leaving for Bayern – who Dortmund face in the Champions League final at Wembley on Saturday – and that the story broke less than 24 hours before their semi-final second leg against Real Madrid, made matters worse. The fee, although hefty at €37m (£31.5m), did not feel like consolation.

Mats Hummels, the Dortmund centre-back, admitted that he was in shock. "Mario is now in the top 10 players in the world and so it was a bad shock for us [to hear that he is leaving]. That night I struggled to sleep.

"To lose someone who knows exactly how we think, who has come through at the club, and still prefers another club, that was hard to take. As [Shinji] Kagawa left, or if [Robert] Lewandowski leaves, then you can kind of understand that, as they are not from Germany, but this has hit us personally."

And then he could not resist having a swipe at Götze. "His transfer shows that we are still not seen as being among the four or five top clubs in the world. There is then the choice of contributing to the club getting there, — or leaving."

Götze's transfer has led to a distinct worsening of relations between Bayern and Dortmund ahead of the final. Before, there was mutual respect. Now, there is acrimony. Two weeks ago, they played out a tempestuous 1-1 draw in the league during which Bayern's Rafinha was sent off for elbowing Jakub Blaszczykowski and the Dortmund manager, Jürgen Klopp, clashed with Bayern's sporting director, Matthias Sammer. That encounter, one felt, was only a foretaste of things to come at Wembley.

Already before that league game, the Dortmund chief executive, Hans-Joachim Watzke, had made it clear that the club were mightily unimpressed by how Bayern had handled the Götze deal. "I have always had a lot of respect and admiration for Bayern but that has cooled a bit now. There have been a few irritations. There will not be [the traditional] lunch before the game on Saturday. Why should we pretend that everything is peace, happiness and pancakes when it isn't? A handshake will be enough."

In the week after the game, he continued to publicly criticise Bayern, saying: "I have a feeling that something has changed at Bayern recently. It doesn't quite add up that [the Bayern president] Uli Hoeness was calling for more solidarity in the Bundesliga only two weeks ago and wanted me involved too. At that point he knew that Bayern were in the process of signing Götze or that an agreement had already been reached. Also [their] interest in Lewandowski was never denied, and no one spoke to us about it."

Throughout the whole saga, Götze has remained silent, his agent doing the talking, saying that if the move had been about money, the player "would have joined Manchester City or another English club".

So is the 20-year-old worth all the hassle and the €37m release clause? Bayern clearly think so and there is no doubt the attacking midfielder is an extraordinary talent with Sammer likely to have been a driving force behind the move. The former Dortmund and Germany sweeper was sporting director at the German FA and responsible for the youth teams before moving to Bayern and told Kicker two years ago: "Mario Götze is one of the biggest talents we have ever seen in this country. I always try to tell players things on the pitch that they may not be seeing at that time. But it is never necessary to say anything to Mario Götze. He is exceptional."

Götze has always been exceptional. Dirk Reimöller, who coached the player at regional level, once said: "Players like Mario don't need to be discovered, they discover themselves."

Perhaps, in hindsight, there was some kind of inevitability of Götze joining Bayern. He was born in Memmingen, Bavaria, in 1992 and lived in southern Germany until he was six, when his father got a job at Dortmund University. After the switch to Bayern was announced last month, Götze's first coach, Helmut Albat, said that Götze used to sleep in Bayern Munich bed linen until he was at least 12.

Götze joined Dortmund as a nine-year-old and progressed through the youth teams at a frightening pace, also being picked at regional and national level, playing for the German youth teams before making his international debut against Sweden in November 2010, becoming the youngest player since Uwe Seeler in 1954 to play for Germany.

By that stage he had already managed to convince his father – a professor – that he should quit school and concentrate on his football. He was still living at home, with his mother doing his washing and cooking for him, and somewhere along the line, a hugely determined and confident footballer developed. Being good was not enough. He was going to be the best.

Götze has talked about his admiration for Lionel Messi and Zinedine Zidane but also how sad it is that players such as Ronaldinho and Adriano have not been able to maximise their careers. Götze had quite a lot of injuries early in his career so that when his friends went off on their summer holidays, he spent time in a rehab centre in Donaustauf, to make his body stronger. It paid off. He made his first-team debut for Dortmund in November 2009 and played five games that season. The next season he played virtually every game as Dortmund won the league, leading up to that heart-warming celebration with Dede. Another title and a German Cup-winners' medal followed in 2012 and this season a brilliant Champions League campaign. That, however, was clearly not enough for Götze and Bayern proved too much of a pull.

Next Saturday, though, there will be no mixed emotions. Götze should have recovered from the thigh injury he suffered against Real Madrid to face his future club, but he will be desperate to win. In the strangest of circumstances he may be hailed by the Bayern fans and denounced by Dortmund's. During the recent league game against Bayern the BVB-fans unfolded a huge banner, saying: "The pursuit of money shows how much heart one has. Fuck you Götze."

Two teams, one final. One player very much in the eye of the storm.