Jonathan Marder is a State Alchemist as well as the Warden of the Amestrian State Grand Prison.
Jonathan Marder is a deceptively intelligent man. Appearing as a stern and gruff prison warden to most people, he is actually a rather kind and caring man. He is incredibly loyal to the people of Amestris, and takes his job as a warden seriously, knowing that his job keeps troublemakers away from the regular populace.
He is also a calm, calculating manipulator. He has been shown to be able to make even Envy, a master manipulator himself, fall into vocal traps. Later, despite being in a life-threatening situation when Envy attacked him, Jonathan was able to turn the field to his advantage and trick the homunculus into putting himself in a cage.
Despite his clear hatred towards the prisoners in his jail, Jonathan does not treat any of them harshly, believing that they can all be rehabilitated and eventually made to join society once more. He rarely has to punish prisoners as a result, as few of them act out against his kind treatment of them.
Jonathan is shown to not fear death. He does not run or back down from the Lesser Homunculi even when the other soldiers started to flee.
Jonathan Marder is known to have romantic feelings for Olivier Armstrong, and follows her without question during the raid on Central.
Jonathan Marder is first introduced early on by Roy Mustang at a meeting of several higher-ups in the Amestrian government. When asked who he was, Edward Elric was told that Jonathan Marder was "Mr. Massacre" by Mustang.
He is not seen again until much later, when rumors of a Philosopher's Stone bring Edward to the Amestrian State Prison, where Marder is the warden. Envy the Homunculus also slips in, disguised as a guard, to keep an eye on Edward.
Marder explains to Ed that the "Philosopher's Stone" that he heard about was in reference to a program the prison used to participate in; trying to use live inmates to produce such stones. The practice stopped years ago, however, when there was no success. However, Marder slips Edward a note, detailing a bit of information about not only Philosopher's Stones, but also what Marder knows about the Amestrian higher-ups, revealing that he believes King Bradley to be involved with suspicious activities. He urges to Fullmetal Alchemist to hurry up with finding out "the Nation's final secret".
Envy finds out about their discussion, and confronts Jonathan. Not knowing what Envy was, the Geomage Alchemist displays his power to Edward in a brief battle with the Homunculus, easily defeating and capturing him. He learns that Envy was trailing Ed and orders the Fullmetal Alchemist to leave the prison, explaining that he had to be on his way regardless. As Edward is escorted out of the prison, Jonathan's makes a call to central, revealing that he has caught a suspicious creature.
One of Central's higher-ups is sent to the prison to ensure Envy's freedom. The unnamed man explains a bit about Father and Envy, and orders Marder to keep secret about the Homunculus, promising him that he, too, can gain immortality on 'the promised day'.
Jonathan Marder is not seen again until the end of the series, arriving in Central shortly after Olivier makes her move. Marder follows her directions and starts to purge Central HQ of the Lesser Homunculus, using his alchemy and sabre. He is later present during the final battle against Father, making several attacks against him before the end.
Jonathan employs powerful earth-based alchemy. In addition to having his transmutation circle tattooed to the palms of his hands, he wears steel-bottom boots with the array etched into them. Under the boots, Jonathan also has the circles tattooed to the soles of his feet.
Using his array, Jonathan is easily capable of transforming the battlefield as he sees fit. When he uses alchemy, the ground rarely stays the same, as it is constantly producing pillars, spikes, and sliding platforms for Jonathan's convenience. Weapons, pits, and even entire buildings are constructed in quick succession, giving Jonathan a massive advantage over most opponents. Jonathan was shown to even swiftly overcome the Homunculus, Envy using his alchemy, and trapped the immortal in a steel cage.
Jonathan is shown as being incredibly dangerous with this alchemy; during the Ishval War he was one of the State Alchemists sent into battle, and met little resistance, racking up a huge death tole. He affected a large area with his power, killing many of his targets easily. Later on, during his early days as a warden, he swiftly quelled a riot with little effort.
Aside from his alchemy, Jonathan employs a sabre in combat, using it to fend off anyone skilled enough to get close to him. He is shown to have great proficiency with his sword, and easily dispatched the lesser Homunculus with them. He also has two Derringer Pistols hidden in his sleeves but, aside from pulling them out, he is not shown using them.
- Like many other Fullmetal Alchemist characters, Jonathan Marder was named after a military vehicle, the Marder, a German infantry fighting vehicle.
- During his battle with Father, Jonathan admits that he had planned a fight against Bradley for some time, indicating a desire to overthrow the current government.