Data Ravelさんのイラストまとめ

His objective would be to unite the Real and Digital Worlds with the power of darkness, converting both into a World of Darkness from which he could rule as the King.

At the end of the series, we have Belial Vandemon in the Digital World being able to absorb and control the power of darkness in any way he wanted.

The Crests of Light and Hope were the ones that freed Qinglongmon from its seal. In fact Qinglongmon, one of the four Digimon that keeps the balance of the world, is the one who holds the spheres of Light and Hope. He explains that these two crests are different from the others.

After the incidents Ken is thoughtful, feeling empty as if he no longer has his heart. This only changes later when he repents of his sins and finds Wormmon's Digitama that when is reborn touches Ken with the "light of life.

Ken's contact with darkness dates back to much earlier in his life, when he was still a child, tempted by darkness through his anger, loneliness and sadness until he became the Digimon Kaiser.

The voices begin to say that because of this power, he was getting closer and closer to the world of darkness. That was the same power implanted in Chimairamon and that started to get Digimon out of control.

Digimon Kaiser thought he could control this power of darkness, but started to hear voices that were driving him crazy. Kaiser boasted of being able to control this power, but as Takeru said, he couldn't even understand what this power was.

There were not only what appeared to be ghosts, but also a black hole at the bottom. There Digimon Kaiser hoped to get data from a Dark Digimon, and he did, by finding Devimon.

Another one of this demonstration is the power of darkness making Digimon Dark-Evolve. Like Greymon/Agumon who evolved into the uncontrolled Skull Greymon and then MetalGreymon, who for being "corrupted by darkness" became a Virus-type Digimon.

Starting Digimon Adventure 02 we have the beginning of the anime with the villain Digimon Kaiser with his "Dark Digivice" with a power to nullify evolutions and de-evolve if necessary (Similar to Apocalymon don't you think?)