Kuromine Zenne is the counterpart of Kagamine Len, whilst Kuromine Zinne is the counterpart of Kagamine Rin.
Both are similar to their counterparts in terms of shaper of both hair and body, but rather than blonde hair and blue eyes, black hair and red eyes replace them. Kuromine Zinne's hairbow is also black, and their outfits have the same color scheme, with a small patch of white on the shoes.
The character item for the both of them is cherries.
Zinne is quiet, seemingly portrayed as a shy, fragile girl, completely opposite of her tomboyish counterpart. She usually is seen hiding behind Zenne, or picking flowers, making pretty necklaces from the stems.
Zenne is the over-protective brother who guards his sister, threatening to bite or attack anyone who dares to touch her. He's very protective over the people he loves, sometimes going a bit too far. Other than that, he likes avocados.
In RP, the twins were created in a lab accident, trying to create weaponized Vocaloids who were sick of human-kind. Sadly, due to the accident, these two were created, yet immediately deactivated and thrown away, until their Master (real creator, RenaKerensky) found them, and took them back to the mansion.