|Dub Name||Dark Spore|
The Dark Seeds (暗黒の種 Ankoku no tane; Dub: Dark Spores) are digital items in Digimon Adventure 02. They infest humans and feed on and amplify their negative emotions.
When a Dark Seed infests an individual, it enhances both their physical and intellectual prowess, allowing them to perform vastly better at academic pursuits and athletics. They are often considered to be "geniuses". However, it also exploits their negative emotions, such as resentment and dissatisfaction with their own life, causing them to think of themself as superior and others as beneath them, and to try and prove it by pushing themself to even greater heights. They become callous and cruel, and act out in extreme ways that were previously totally uncharacteristic of them. They are also prone to inconsolably angry outbursts when things do not go their way. Because of this, feelings of positivity and contentment prevent Dark Seeds from growing or the condition from progressing.
Dark Seeds feed on the negative emotions of their host and, as time passes, they sprout, then blossom as a Dark Flower (暗黒の花 Ankoku no hana), which gives off powerful dark energy. Dark Flowers are not visible to the human eye, but Digimon can see them; Ichijouji Ken theorizes that this is because they are only a mental phenomenon rather than a physical object. Supposedly, if Dark Flowers are not harvested, they will keep growing and totally overtake the host, turning them into a Dark Tree (暗黒の樹木 Ankoku no jumoku).
Since the Dark Seeds are just data, they can be scanned and copied. There is a difference between the original Dark Seeds, such as the one that infested Ken, and the duplicates created from that one by Oikawa. The copying process was imperfect, and they are manually implanted, so the results differ. Supposedly, original Dark Seeds are more adaptable.
The only way to remove a Dark Seed appears to be for the power of its Dark Flower to be harvested, so in other words, only Oikawa Yukio is thought to be able to remove them. Once a host's Dark Flower is harvested, the host is left exhausted and depressed.
The presence of a Dark Seed in an individual can be seen as a black, barcode-like mark on the back of their neck.
A flashback depicts the origins of the first Dark Seeds. When Ichijouji Ken and Akiyama Ryo defeated Millenniumon, Millenniumon released a wave of Dark Seeds. Ken pushed Ryo out of their way, but one struck him and burrowed into the back of his neck, causing him immense pain. After this point, the Dark Seed begins to grow in him as a result of both his anger at his brother Osamu and grief at his death, and after he receives an email from Oikawa Yukio, he enters the Digital World again and becomes the Digimon Kaiser, as a pawn of Oikawa's plans.
In the end, his final defeat and the sacrifice of Wormmon force Ken to reckon with the reality of what he had done as the Kaiser and how he had caused himself to relive the same grief he had felt when Osamu died, and he snaps out of it. After this point, the growth of Ken's Dark Seed is halted. Ken thinks that this is because he had finally realized that his parents love and care for him.
Oikawa's master plan is to harvest the power of Dark Flowers and enter the Digital World. He and his agents, Archemon and Mummymon, begin approaching disaffected children and tempting them with talk of the Dark Seeds and the Digital World. After Christmas 2002, twenty children willingly go with him to receive Dark Seeds so that they can become like Ken, but they are widely presumed by both the media and the Chosen Children to have been abducted. He then uses the children to coerce Ken (whom he had previously identified as having a Dark Seed at Osamu's funeral) into coming with him, so that he can copy Ken's Dark Seed with a hand scanner and use that data to implant replica Dark Seeds in the children. After doing this, he has no further use for Ken, so he releases him.
Demon also has plans involving the Dark Seeds and launches an attack on Tokyo, so that he can take Ken (and, later, the other Dark Seed children) from Oikawa and use their Dark Seeds. The Chosen Children foil his plans by trapping him in the Dark Ocean.
After the defeat of Demon, Oikawa allows the children to return home, so that their Dark Seeds can grow and flower. Takaishi Natsuko uses her connections to get the names and addresses of all the children who Oikawa had abducted, and the Chosen Children begin tracking them and attempting to convince them not to listen to Oikawa, without success. On December 29, 2002, Kawada Noriko's Dark Seed blossoms into a Dark Flower, and Oikawa harvests the power from it.
On December 31 2002, the remaining nineteen children gather at Hikarigaoka on Oikawa's instructions, so that they can enter the Digital World. However, they are instead sent to a world of dreams, where Vamdemon reveals himself as the one controlling Oikawa and the mastermind behind Oikawa's plan. He harvests the power of the children's Dark Flowers and uses it to become Belial Vamdemon. Although the children all feel hopeless, the Chosen Children inspire them to have faith in themselves and their ability to achieve their dreams, and they all gain partner Digimon and D-3s of their own. Their hope contributes to the destruction of Belial Vamdemon. Ken is confident that as long as they continue to believe in themselves like this, their Dark Seeds will never sprout again.
Individuals infested with Dark Seeds
|Ichijouji Ken||Ken's Dark Seed originates directly from Millenniumon. His Dark Seed caused him to become the Digimon Kaiser, and during this time he became well known in the media in Tokyo for his exceptional academic and soccer achievements. The Seed is neutralized after his defeat, when he reconciles with Wormmon and his parents. All of the Dark Seeds used by Oikawa Yukio are copied from Ken's.||"Invasion of the Demon Army"|
|Kawada Noriko||One of the children whom Oikawa infested with a Dark Seed copied from Ken's. Her Dark Seed is the first to sprout into a Dark Flower, which Oikawa harvests to power himself up enough to mortally wound Black War Greymon.||"The Deadly Struggle with the Dark Digimon"|
|Yoshizawa Takashi||One of the children whom Oikawa infested with a Dark Seed copied from Ken's. His Dark Flower is harvested by Vamdemon after they enter the world of dreams.||"The Deadly Struggle with the Dark Digimon"|
|Shibata Hiroshi||One of the children whom Oikawa Yukio infested with a Dark Seed copied from Ken's. Although he is not identified on-screen, his Dark Flower is probably harvested along with the other children (except Noriko) by Vamdemon in the world of dreams.||"The Deadly Struggle with the Dark Digimon"|
|17 other children||In total, Oikawa rounds up and infests 20 children with copies of Ken's Dark Seed. Vamdemon harvests all of their Dark Flowers after they all enter the world of dreams.||"The Deadly Struggle with the Dark Digimon"|