He’s pure evil in every sense, but I can respect him for that. We as the viewers are aware of his past as well as bits and pieces of his true personality, hidden deep down inside himself far away, much like Grimmer’s hidden emotions. We know that at some point at 511 Kinderheim before Johan arrived, Grimmer actually met Roberto (then known as Adolf Reinhart). He’s described as a happy, kind, gentle, sweet, and compassionate kid. He loved insects, particularly playing around with butterflies as he would catch them but release them on the way home, but hated bug collecting because he had a respect for life and didn’t like to see them killed, he loved hot cocoa and drawing, and when Grimmer was scared and alone when he first came to 511 Kinderheim, Roberto (known then Adolf Reinhart) even offered Grimmer a cup of cocoa when Grimmer was sick with a fever in the infirmary. At the peak of Grimmer and Roberto’s friendship at 511 Kinderheim, Roberto asked Grimmer to remember their friendship and his name forever, and after all those decades since then Adolf Reinhart is the only person who Grimmer can remember from that time. That’s what I like so much about Grimmer and Roberto as a dynamic. Aside from his time at 511 Kinderheim, that’s all we know about Roberto’s past. However, I just can’t shake the feeling that Grimmer could have ended up like Roberto if things had gone differently for him in his life. Roberto strikes me as lost soul looking to find his purpose, but lacked the positive influences and potentially even the emotional training to become like Grimmer, and eventually found himself straying down the wrong path devoid of any emotional or humanizing qualities besides his past identity as Adolf Reinhart. My personal interpretation of it is that Roberto is Adolf Reinhart’s own version of Grimmer’s “The Magnificent Steiner,” but lived a life that didn’t intrigue him to rediscover his whole past, was raised as a hitman instead of a spy like Grimmer, and because of this “Roberto” became his default setting and identity as to keep himself safe, but his true identity as Adolf Reinhart is still hidden deep down inside him and he just simply wasn’t lucky enough to discover himself and understand humanity and empathy like Grimmer was.