Bruno was a close friend of Baron Reinhold. He was a skilled technician, and built Matthew to serve as the Reinhold's butler. When the baron's wife, Lady Violet, died from influenza, he built a robot replica of her for the baron and his daughter Flora. But the baron was very distressed at how similar it was to Violet, so Bruno wiped its memory and personality clean. In its place, he created Lady Dahlia, with whom the baron was happier with, but scared Flora.
When the baron was told he was terminally ill, he had Bruno build St. Mystere and all its residents, so Flora would have a safe environment surrounding her. Bruno took over Flora's care after the baron's death. He also kept the robots of St. Mystere in good working order, which became needed more often as the robots aged.
Bruno is first seen near the market shoving an unconscious Ramon into a bag. Professor Layton and Luke witness this and give chase, but Bruno manages to escape back to the tower. Later on in the game, after falling through the floor in the tower, the two meet Bruno again in a workshop-like room. He reveals himself to be a close friend of the late baron who repairs the villagers when they malfunction.
After the game, Bruno remains in St. Mystere, continuing his work of maintaining the villagers as normal.