As the head of the Amadeus Syndicate, the Doctor helps Morden to obtain new weaponry and also creating his own army. He controls the Amadeus Mother Computer, a three part contraption. After defeating him, the base begins to collapse while he is still stuck inside the last machine. Whether he survived the destruction of the Mainframe base or not is unknown.
The Doctor appears several times in Metal Slug Attack. Just like in Metal Slug 4, he is affiliated with the Rebel Army although in some occasions.
Not having any children of his own, he created various AIs to mimic them, as shown with White Baby and Iron Fortress as both are AI appearing as children, and has grown attached to them as a father figure.
In "Amadeus' Revenge" Extra Ops, he tests out a new Type γ Mother Computer and is delighted with the results. When confronted by the clumsy Rumi, he tries to kill her with the machine's lasers, but she dodges all of them. Rumi then counterattacks by throwing grenades, but it appears to be clumsily thrown. The Doctor laughs at her incompetence, just as the grenades fall on top of the Mother Computer and destroy it. The Doctor survives, but is clearly not pleased.
While developing new weapons, the Syndicate are attacked by the Invaders Annette and Schwarz Metzelei. Although urged to evacuate, he is uncertain, as his plans would be set back considerably if he had to leave. Fortunately, the two Invaders eventually leave after getting the desired results, although the Syndicate has taken heavy casualties.
The Iron Fortress mentions him when White Baby gets damaged from Allen O'Neil's Red Sergeant Drill. He likely oversees White Baby's repair from the injuries she sustained in battle.
The Amadeus Syndicate eventually develops the Sea Satan II. When two young children sneak into the facility, the Doctor unleashes his weapon on them, feeling remorse for having to kill children, but must do so to protect the secrecy of his weapon. Much to his surprise, the two destroy the Sea Satan II and he retreats, commenting on their strength.
He later decides to invest in making stronger units, first off by developing golden variants of the Morden Robot and his Mother Computer, sending them off in an operation against the Regular Army. Though the results are promising, the mission ends up being a failure due to the intervention of additional reinforcements.
The results eventually made him decide to continue on this investment, overseeing one of his Brave Guerriers being painted gold. Alma questions this decision as research would give better results, but he scolds her and states that immediate results (showing off opulence and wealth) would be more effective than an investment. This plan eventually crumbles after the other armies destroy the Brave Guerrier Type-G, and he becomes annoyed when he spots Alma scavenging the remains for parts to resell.
After Iron Fortress runs away due to being constantly teased, Alma orders the Syndicate to get her back, stating that she's the "old man's favorite". The Doctor is clearly not amused by this despite the fact that they recovered the Iron Fortress. As punishment, he shutters her current laboratory and moves her into another one with no running water or electricity.
He appears in Another Story in the chapter "Guilty Child", where Syndicate soldiers bring Abigail to him. He is initially confused by her aggressive stance, but when she and Allen O'Neil mention a little girl's voice, he becomes horrified after realizing the culprit. White Baby forcefully places him into a Mother Computer, though he is freed when the two officers destroy it. He explains White Baby to them and promises to assist them, though he is concerned for White Baby's well-being when Abigail states that she will destroy everything in Morden's path to world domination, which Allen is able to interpret.
Sometime after the Professor destroys the Sol Dae Rokker, the Doctor and several researchers find its remains and fuse it into an anima form to take over the world. However, White Baby arrives and causes havoc, leaving the Doctor at her mercy. The Doctor states that he didn't design her to destroy humanity, which she attempts to counter by stating that the strong must control the weak. He explains that there are others stronger than her, something which the AI finds amusing. Navy and Vita soon arrive, due to the former wanting to destroy Anima to prove she is stronger than the Professor. After exchanging some insults, Navy destroys Anima. The Doctor comments that it will take thousands of years for Anima to be recovered, and states that the Professor wasn't just skilled in combat when Navy brags that she is better than him. This suggests that he used to be good friends with the Professor, or admired his talents.
During a Halloween party, the Doctor learns Alma used the Jade John and Type γ Mother Computer without his permission. He catches her by surprise after the zombified P.F squad defeat Beatriz, and states that her actions will not go unpunished.
- The Doctor reuses the sprite of Parker, the businessman/representative of a video game company who had his briefcase stolen by the player in Metal Slug 2/X.
- The Doctor and the Invader King are only final bosses which have their own final boss theme.
- The Doctor has unused sprites of himself walking and smoking a cigar. Said walking sprites are redrawn for the Doctor Type: AI's walking animation in Metal Slug Infinity.
- Prior to his "name reveal" in Metal Slug Attack, the Doctor was usually referred to as "Amadeus" stemming on how the Rebel Army and its infantry are sometimes officially called Morden's Army or Morden Soldiers. "Amadeus" in Metal Slug Defense and Metal Slug Attack only refer to the Syndicate and the three Mother Computer contraptions.