The case of the Demogoblin is is unique, as it is not and never has been a human being. Demonic psychology is an unexplored field of study, yet the creature does have many traits that correspond to human psychology. It is dedicated to receiving salvation and redemption in God's eyes by cleansing the world of all sinners. Forgiveness is not a possibility for the Demogoblin, who meets out summary execution to anyone it considers evil, which is everyone, excluding children.
The demon eventually known as Demogoblin arrived in this reality after being summoned by the higher ranking demon known as N'astirh. New York City had been overwhelmed by a demonic plague, led by N'astirh, and the demon had been visited by Jason Macendale, aka Hobgoblin. He offered N'astirh his soul, which didn't interest the demon. Macendale had amused him and he bonded him to a demon. (Spectacular Spider-Man (vol. 1) #147) The possession granted Macendale greater strength and super powers, but the demon was slowly taking control of him. Instead of fixating on money and killing Spider-Man, the Hobgoblin obsessed over purifying a wicked world.
The struggle between the two of them took a turn when the demon split from Macendale, just as the duo was battling Spider-Man. Repulsed by the creature’s ugliness, Spidey dubbed the demon “Demogoblin.” Exhausted by the separation, the demon fled, saying that the Lord must want it to spare the two of them. (Web of Spider-Man (vol. 1) #86) The truce didn’t last long and after another fight with Spider-Man and Hobgoblin, Demogoblin found an ally in the mindless Spider-Man doppelgänger. The two formed a psychic bond and Doppelgänger became Demogoblin’s sidekick. (Spider-Man (vol. 1) #24)
While on his mission to murder all sinners, Demogoblin came across Carnage, Shriek and Doppelgänger, who had become their pet. After a short fight, Carnage convinced the demon to join them in their rampage across Manhattan. (Amazing Spider-Man (vol. 1) #378) The relationship between Carnage and Demogoblin was not a good one, as the serial killer was obsessed with the concept of a meaningless existence and Demogoblin believed in a divine plan. (Spectacular Spider-Man (vol. 1) #201) Regardless, the “family” worked together to bring mass slaughter to New York and battle the assembled heroes that stood against them.
After leaving his adopted “family,” Demogoblin decided that he had strayed from his true path and needed to settle his old accounts with Jason Macendale. (Spider-Man (vol. 1) #46) His final fight with the Hobgoblin took place in a church and one of the building’s columns had been weakened by the battle. Demogoblin saw a young girl in danger from the crumbling structure and begged Hobgoblin to save her. Hobgoblin refused and Demogoblin’s final act was to escape the Hobgoblin and shove the girl out of the way. However, it was crushed by the column. (Spider-Man (vol. 1) #48)
Years later, the demon was summoned back to earth by Carnage, who sacrificed Shriek in a ritual. The demon possessed her corpse and took on a feminine appearance, hence called Demagoblin by Carnage. Demagoblin possesses the powers of both Demogoblin and Shriek. (Absolute Carnage: Lethal Protectors #2)
After Knull, God of the Symbiotes, came to Earth and conquered the planet, Demagoblin showed it’s devotion to the deity in worship and praise. Knull was annoyed and told the creature that it talked too much before battering it away. Later, the demon formed a cult made of orphaned children, which it called it’s “acolytes.” The cult was confronted by Scream but the story was unfinished. (Scream: Curse of Carnage #6)
A zealot is defined as “a person who is fanatical and uncompromising in pursuit of their religious, political or other ideals.” As shown in his philosophical difference with Carnage, it rejected his idea that life was meaningless but said the universe is nothing but order and pattern. There was no compromising with either of them. Death was the only solution to the sinful world we live in and it took it on itself to carry out a nearly universal death sentence.
Demogoblin has the characteristics of many fanatical leaders. Common traits are:
Mental health counselor Steve Hassan, himself formerly a member of a cult, says that a destructive cult is an authoritarian regime. It uses deception when recruiting and mind control to keep members dependent and obedient. Stephen J. Morgan, a faculty member with the American Management Association/Management Centre Europe in Brussels, stresses the importance of understanding cult mentality when fighting terrorism. He says that cult leaders are often psychopaths with a lust for power and take ideas from religion, politics, and psychology to control followers. Mind control can be used to filter thoughts and behaviors into "fanatical faith and belief."
While Demogoblin's primary goal was the elimination of all sinners, it was also fixated on Jason Macendale. Demogoblin treated him like an obsessed ex-partner running after a former lover. The stages of demonic possession are similar to that of the stages taken in an abusive relationship. Supposed possession by evil spirits can be caused by many things (Macendale took the very direct approach and asked to be possessed) but there are four stages of demonic activity: infestation, oppression, obsession and possession. Father Gabriele Amorth, chief exorcist of Rome, said that infestation can be compared to haunted house cliches: furniture moving by itself, strange smells with no cause, footsteps with no one around, etc. Oppression features physical attacks, frequent illnesses, major depression, financial trouble and employment problems. If they all happen at the same time, it could be a demonic influence. Obsession finds the person's life entirely under the thumb of the demon. They have a hard time functioning as their every thought is based on what is happening in their life. Sleep becomes impossible and thoughts of suicide become common. In the end, the final stage is actual possession. At that stage the human is so drained that the demon can take occasional control of the person's body. Free will is never completely lost, but badly compromised. Signs of possession are superhuman strength, speaking languages they don't know, unusual hatred of holy objects and knowledge of events that the person couldn't know.
One the other side of the same coin, Dr. Joni E. Johnston laid out three ways in which a relationship with an obsessed former partner progresses. Early in any relationship, healthy or not, is the Absorbed stage. You and the other person are focused on each other and you want to learn all about each other. In an unhealthy relationship, it all happens too quickly and too deeply. Next is the Agitated stage. In a bad relationship, the obsessed partner begins to control the other. They call, text, or email many times a day and becomes jealous easily. They become overly afraid of losing their partner and become mistrustful. Finally, is the Aggressive stage. The relationship becomes aggressive if attempts to control the partner have failed or if the relationship ends. The obsessed former partner may threaten suicide, or try to meddle in your personal life. In extreme situations, there may be stalking, threats and physical violence.
In short, Demogoblin/Demagoblin is a fanatical cult leader obsessed with murdering sinners and rescuing children. Regarding the Hobgoblin, it has the mentality of a spurned former partner. Medications such as anti-psychotics have been shown to somewhat help those with psychopathic traits, but medication is useless if the patient refuses to take them. (Assuming they even work on supernatural creatures.) Therapy can help show such a person that they bring about their own problems but that would require the demon to listen to other views and not twist the facts to suit itself.
In many ways, Demogoblin was a lone wolf, working alone when killing sinners. At other times, it took on followers, yet worked poorly in a team. It struggled with Hobgoblin and Carnage but found obedient followers in Doppelganger and it's "acolytes." A mindless monstrosity and impressionable children made for excellent minions. It's uncertain which god the demon thought that it was serving, but it was very unexpected that it knelt before Knull.