In many ways, she looks similar to Biyomon. The blue tail-feathers of her counterpart are instead a deep purple, however, as are parts of her striped head-feather and the tips of her face. The rest is a deep gray, only just lighter than black.
She accompanied her partner on her hunt for the tamers, and specifically the Angels, even though she tries to gently talk her out of it. DarkBiyomon is one of the only beings that Chiyo seems to actually care about. When the girl begins to "pretend" to be the tamer's friend, the digimon actually hopes she will decide to stay friends with them. She wants Chiyo to have a real life beyond her Demon-fueled hate. But, when the girl chooses to go through with her plan to turn the girls against their boyfriends, DarkBiyomon stood by her until the Second Demon's death.
At first, Chiyo's death left DarkBiyomon with the desire for revenge. She tried to attack Ryder during the middle of the night. When that didn't work and she gave up that plan, she was taken to the Nonaka residence, where she made a deep connection with Seiko. At Chiyo's funeral, the girl's D-arc attached to Seiko's wrist. This makes DarkBiyomon the only digimon to switch partners. So far, her partnership with Seiko has been fairly basic with no combat involved, but Seiko offers a sympathetic person to confide in to the heart-broken rookie.