“La Casa De Papel” also known as “Money Heist” is now one of Netflix’s most popular series. It's one of the few TV shows in which all protagonists are likeable characters, each one with their own background story and depth. They're not very good people, but usually, in fiction, the dysfunctional and dark characters are the most fascinating ones.
That's also part of why Berlin, one of the robbers, is so loved by the fans. He certainly isn't an example to follow nor the kind of person you'd want to meet in real life, but he manages to make the story more intriguing and interesting to watch. As a warning, there's a season 2 finale spoiler ahead so if you aren't caught up, be careful before you keep reading.
He’s calm and intelligent, almost elegant in his every move. He’s considered sexist by Nairobi, who changes her mind about him in the finale, but his sense of superiority isn't just about gender. It's actually about him needing to feel superior over literally everybody regardless of what gender they are. He's a narcissist with some homicidal tendencies although he's still capable of being loyal to his brother, the Professor, and to the plan. It also often seems like his sense of superiority hides a feeling of insecurity probably relating to his rare terminal illness, which he struggles to come to terms with. In spite of all the cruel tendencies he has, he's still capable of some good deeds like making the sacrifice he did in the finale.
He seems to deeply care about two values: honor and dignity. This also perfectly explains why he sacrifices himself: he knows he only has seven months of life left because of a rare illness, and he knows that in the last months of his life he is not going to be able to do even the simplest things like eating without help. That illness would give him a slow, painful death that would also take his dignity awa. Instead, dying while saving the mission -- which is extremely important not only to him and the robbers, but also to his brother -- is the most glorious death he can have.
And although he used to be, after Tokyo, the one who caused more disagreements than everybody else, in the finale even Nairobi changed her mind and realized that he wasn’t all bad. She even begged him not to go in one impressive scene where he may have understood that even though he isn’t such a good person, he didn’t need Ariadna (another breaking character who unfortunately crossed Berlin’s path) by his side to know that he wouldn’t die alone which makes us understand why he wanted her to stay with him while shooting the cops.
He is, therefore, a quite complicated and weird character, but whose every scene was startling and entertaining and although he won’t be in the upcoming third season, he’ll always be one of the characters who made the show more interesting and as great a it has been!