Parasite Monsters are parasites that takes control of a person's mind. These parasites manifest in the host's Deck as the monster card "Fusion Parasite" and warp their strategy into one that utilizes Fusion Summon, regardless of their Deck's usual play style or the host's Dimension of origin. Despite their organic appearance, the monsters are advanced form of Real Solid Vision and thus require control from their cards to function properly.
Parasite Monsters are created by The Doktor with Leo Akaba's ARC System. They are developed to reside inside the host’s brain, allowing them to collect the host’s memory data and analyze them and have a strong control on the host's mind. The Parasite Monsters are programmed to make their hosts become loyal to The Professor. As seen with Celina, Rin and Lulu, the parasite monsters can make their hosts act as sleeper agents, allowing them to retain their normal personalities until the time is right. As seen with Lulu, the true nature of the parasite is to suppress the original personality of that person so that they lose control of their bodies and most of their consciousness. If there is a strong enough external stimulus, it is possible for the host to break free of the parasite temporarily. According to Aster, the host will be completely free from the influence of parasite when the Doktor is defeated. Defeating the host will not free them from the Parasite's control, whether or not their "Fusion Parasite" cards were destroyed during the Duel or if the host broke free momentarily.
Parasite Monsters are also able to quietly enter a host, as shown when one entered through Yuya's ear during his Duel with Celina and Lulu. At this point, however, it was also shown that Parasite Monsters can be repelled, as it invoked Yuya's awakening for a moment, allowing The Darkness to immediately neutralize and destroy it.
- Celina (freed after the Doktor was sealed into a card.)
- Rin (freed after the Doktor was sealed into a card.)
- Lulu Obsidian (freed after the Doktor was sealed into a card.)
- Unnamed Duel Academy Student (freed after the Doktor was sealed inside a card.)
- Zuzu Boyle (freed after the Doktor was sealed into a card.)
- Yuya Sakaki (failed, destroyed by the Darkness.)
- ↑ 1.0 1.1 1.2 Yu-Gi-Oh! ARC-V episode 127: "Revival Zero"
- ↑ Yu-Gi-Oh! ARC-V episode 115: "Duel Pirate Captain Solo"
- ↑ Yu-Gi-Oh! ARC-V episode 117: "The Sinister Bell's Chime"
- ↑ 4.0 4.1 Yu-Gi-Oh! ARC-V episode 119: "The Little Bird Trapped in Darkness"
- ↑ Yu-Gi-Oh! ARC-V episode 118: "Survival Duel"
- ↑ 6.0 6.1 Yu-Gi-Oh! ARC-V episode 125: "The Blazing Dragon"
- ↑ Yu-Gi-Oh! ARC-V episode 123: "The Glorious Machine Dragon"