Following considerable transfer speculation, Madrid eventually completed the signing of Reinier in January from Flamengo in a deal reportedly worth a potential €35million.
Due to Reinier's involvement with Brazil in CONMEBOL's Pre-Olympic Tournament, in which the Selecao finished second to confirm their place at the 2020 Olympic Games, the 18-year-old was unable to join up with Madrid straight away.
But the attacking midfielder, who has been compared to former Madrid attacker Kaka, was presented to the Spanish media at the Santiago Bernabeu as he prepares to make his official bow for the club's Castilla team.
"Everything that I experienced in childhood crossed my mind [when signing], since I left home with my father, I arrived in Rio alone, without my mother, without my sister," a visibly emotional Reinier told reporters before being encouraged to take a brief break by club director Emilio Butragueno.
"When I talk about my family I get very emotional because I am sure it was all thanks to them [that I'm here]. I thank them, also those [family members] in Brazil, like my grandmother. Since I was a child they helped me achieve my dream.
"This is a very happy day for me. I am fulfilling a childhood dream. We always talked about how amazing it would be to get here. I want to be part of the history of this great club.
"It is the realisation of a dream. Playing in Madrid was the dream of my father, my sister, my mother."
Reinier will initially link up with Castilla for the rest of the season, as Vinicius Junior and Rodrygo did before him.
And while playing for third-tier Castilla may represent something of a culture shock compared to Campeonato Brasileiro and Copa Libertadores champions Flamengo, regarded as the most-popular club in Brazil, Reinier is relishing playing under the guidance of Madrid icon Raul.
"Flamengo is the biggest team in South America, but I am happy," Reinier added. "I have already trained with Castilla, they are great people, I have already met Raul.
"He's one of my idols and he welcomed me. I'm very happy with our talk. He wished me luck, and I'm sure I will do my best. As we say in my country, I will give my life for Madrid.
"Tomorrow [Wednesday] we will be very well together again and I will be ready for Sunday."
Reinier could make his debut at home to Segunda B1's bottom side San Sebastian de los Reyes on Monday (AEDT), with Castilla – who are eighth – hoping to close in on the play-off spots.