An old, reclusive automail master, his lifelong dream was to create automail with hidden cannons inside them. He got the chance to realize this dream with Paninya's automail legs. Winry asks him to take her on as an apprentice, but he directs her to Garfiel instead, despite Winry helping deliver his grandson.
When he discovers that Winry is Pinako Rockbell's granddaughter, he becomes extremely flustered, apparently due to memories of the "Pantheress of Resembool" that he'd rather not recall ("Leopardess of Resembool" in the dubbed anime).
In the anime, there's no mention of a desire to build hidden cannons, though he does install one into Paninya's right leg. He declines to sell an automail arm to a young wealthy man because it's designed for a fighter, and the young man doesn't truly need it. By the end of the series, he is seen assisting Winry in her training to become an even better mechanic.
