| "I once thought I could save the world... now look at it"
— Spoilers for Deus Ex: Mankind Divided follow!
Compared to other ARC members, Marchenko is outspoken and has radical views regarding how to resist the oppression of transhumans. He is suspected of being responsible for multiple terrorist attacks, carried out in an attempt to further ARC's cause. This is in spite of the fact that Talos Rucker, the leader of ARC, is opposed to violence.
Marchenko is both charismatic and intelligent. He is also well versed in the history of past revolutionaries.
Not much is known about Marchenko's life prior to him joining ARC other than that his parents were illiterate railway workers. Even he himself did not receive proper education, leaving school after 10 years to become a shift worker on a drilling gang for shale-gas deposits in eastern Ukraine.
Marchenko ran into trouble in 2011 with a group of Pro-Russian separatists and ended up with severe injuries to his body, causing him to be hospitalized. At some point, he also served time at the Ukrainian prison Lukyanivska. Afterwards, Marchenko disappeared from the records for 12 years, until 2023 where he suddenly resurfaced with a wife (Alisa Maratovna - a suspected Russian Intelligence Agent, whom he married in 2021) and newborn daughter (Raisa Viktorichna) in Belgorod, Russia. By this point in time, he had still not yet been augmented. He and his family disappeared shortly prior to the Aug Incident.
After 2027, Marchenko entered Útulek using the name Viktor Melnik. It is speculated by Dr. Auzenne that the name could be a tribute to someone else, possibly Alisa Maratovna whose maiden name was Melnika. His wife and child were not with him when he arrived at the complex, and according to the State Police, Melnik was the instigator of a few incidents in which he "stood up" to them while they were performing their duties. It is unclear as to when exactly he started using the name "Marchenko" again.
Deus Ex: Mankind DividedEdit
Adam Jensen first encounters Marchenko during his search for Dr. Talos Rucker in Golem City, where he is witnessed taking down a rampaging police Drone single-handedly. After a brief exchange of wisdom, Marchenko takes off with the drone and his comrades, but not before dissuading Jensen from investigating any further. Jensen then requests a background search on Marchenko, but didn't find any usable information. He is not seen again until after Rucker's assassination, which was strongly implied to have been orchestrated by him, and Jensen's forced extraction from the complex.
Back in Prague, should Jensen choose to pursue MM12: Confronting the Bomb-Maker, it is revealed that the bombing of Růžička Station was an intentional plot by him to pin the blame on ARC, and carried out through his proxies of Allison Staněk and Ivan Berk.
Upon reaching the G.A.R.M. facility, Jensen is inexplicably ambushed by Shadow Operatives and Marchenko, who by that point is revealed to be an Illuminati mole. Marchenko promptly injects Jensen with a sample of the Orchid before leaving for Prague to discuss his deal with Radich Nikoladze, unaware of the agent's survival and recovery.
Marchenko is encountered for the last time at the Apex Centre in London, where he attempts to kill Nathaniel Brown and other delegates with the Orchid, as the Illuminati want the Human Restoration Act to pass. When their plot is discovered, Marchenko hails Jensen over InfoLink, demanding that the agent confront him personally or watch as he detonates the explosives planted in the nearby towers, killing hundreds. One way or another, the two meet in the atrium where combat eventually ensues and Jensen emerges victorious.
Depending on how the player engages him, Marchenko can be knocked out and incarcerated by the police, gunned down, or terminated via his killswitch.
Both of Marchenko's arms as well as his right eye have been replaced with mechanical augmentations. His smaller right arm can open up into a laser cannon which he will wield against the player during the final battle.
As an agent of the Illuminati, Marchenko has a bomb implanted inside his body that can be activated with a killswitch, known as Damocles' Sword, in case he ever stepped out of line or is compromised while on mission. Unlike other killswitches used in the series, which are spoken phrases, Damocles' Sword is a single physical object almost identical to a Multi-Tool, except white and has a skull icon in place of the progress meter. Booby traps are put in place so that killing him with this device will cause his body to explode, potentially maiming or killing his opponent should they try to recover his remains.
- Marchenko was apparently supposed to be a leader or high-ranking member of sorts within the ARC chain of command as depicted in the trailer. In the final build he seems to be a recent insertion into ARC by the Illuminati as lampshaded by another member during a news interview.
- Through the assassination of Talos Rucker it would be safe to assume that he would rise to such a position as the story progresses.
- Marchenko maintains two e-mail addresses, one in his name which he uses to address most members of ARC, and another named Oldblueeye which he uses to communicate secretly with other members of the Illuminati. For whatever reason, Marchenko contacts Tibor Sokol under the second alias.
- Marchenko is the final "boss" of the game, and can be either killed or taken down non-lethally. A killswitch can be used to instantly wipe him out without a fight that grants the achievement Laputan Machine, but will void Pacifist.
- If Jensen uses the killswitch on Marchenko, he first offers to give him the device on the condition that the latter will surrender to the authorities. Marchenko refuses, because the Illuminati will just find another way to kill him.
- As he is heavily augmented like the Tyrants of the previous game, Marchenko is capable of resisting and countering Jensen's takedown attempts if they were to fight head on. EMP damage or an electric shock can temporarily leave him vulnerable, however, and taking him down will net a unique XP bonus and a Praxis Kit can be looted from his body.
- He has a fondness for tranquilizer rifles and stun guns, suggesting he's not quite as brutish as one might think. Non-lethal players would do well to loot his ARC HQ weapon lockers, cases, and G.A.R.M. office.
- Marchenko is seen wielding a Linebacker G-87 MSGL against Adam Jensen in the reveal trailer, though he does not make use of it when fought in the game proper, opting to go with Hyperion, the laser cannon implanted in his right arm instead.
- A usable unit of the launcher can be found in a weapon locker inside his office at G.A.R.M. station however, as a probable nod to this.