Sweet and even-tempered, Mattias is gentle boy who looks after others. He and Tobias seem to be closer to each other than some of their other siblings. Mattias cares about Tobias's physical and mental well-being, and goes out of his way to try and help his brother when he can, even when Tobi literally pushes him away. He is prone to daydreaming, in part due to his narcolepsy.