Reiner had completely incorporated Marcel's personality into his own. He built up a reputation of being a passionate and honest person with a strong sense of duty who takes his role as a soldier very seriously and encourages others to do the same. However, he was also noted to have a kind heart and a tendency to always think of others before himself, taking on extra burdens for the sake of his comrades. He was stated to be the "big brother" of the other trainees.