A brilliant alchemist, Hawkeye postulated the complex and intricate theorems necessary to apply flame alchemy at its most powerful and efficient level but refused to pass on his flame alchemy secrets to his pupil, Roy Mustang, thinking them too dangerous for a young and naive student. Riza describes her father as a frightening man with whom she did not generally associate and could not at all relate. Afraid of his life's work being destroyed and what his Flame Alchemy knowledge could do if it fell into the wrong hands, Master Hawkeye refrained from keeping notes in the normal fashion and, instead, tattooed a large Transmutation Array containing the culmination of his craft and findings on his daughter's back, perhaps further straining - or serving as an indication of - the Hawkeyes' already shaky relationship.
Master Hawkeye, as an independent alchemist, appears to have held some disdain for the State Military (much like Izumi Curtis), as revealed by his flippant reaction to Roy's enlistment during the Ishval Civil War as well as his preference of living in squalor with all his genius over joining the State Alchemist Program.
As Roy returned to his teacher's house in an attempt to get hold of the theory of Flame Alchemy to enlist as a State Alchemist (he was just a regular soldier at that time), Master Hawkeye revealed to him his daughter possessed the theory and succumbed to illness, coughing up blood as he died in Roy's arms, but not before apologizing to his daughter for not doing anything for her, showing that despite her claims of him being a frightening man and being immersed in his work, he truly did care for Riza.
- While Master Hawkeye's first name was never given in the manga, Fullmetal Alchemist: Brotherhood's 30th episode states his name and birth year upon his tombstone.
- Master Hawkeye slightly resembles Shimei, an antagonist from Arakawa's manga series Hero Tales.
- Berthold Hawkeye may have gained his given name from Berthold "Black" Schwartz, a German alchemist of the thirteenth or fourteenth century who is said to have discovered gunpowder and the cannon. He was sometimes nicknamed the "Powder Monk".
- Fullmetal Alchemist: Brotherhood, episode 30