A Rainbow Drinker is a troll Vampire. The term Rainbow Drinker comes from the way the Hemospectrum could be referred to as a rainbow, making a Rainbow Drinker a troll who drinks a rainbow of colors. The creatures are first introduced as fictional and, like their earth counterparts, play a large role in Alternian literature and popculture. As the story progresses, however, we learn that Rainbow Drinkers are real.
Rainbow Drinkers have white skin that normally glows. However, as seen with Porrim and later Kanaya, some Rainbow Drinkers can turn off this glow. Their scleras appear bright yellow instead of the usual orange. Currently, the reason for this is unknown.
The process in which trolls turn into a rainbow drinker is mostly unknown. Kanaya becomes a rainbow drinker after Eridan kills her. One possibility is that Karkat's attempt to kiss her back to life awoke her Drinker status due to his status as a Hero of Blood. It is hinted at that a troll is born a Rainbow Drinker and does not become one when Aranea talks about Porrim's backstory in Openbound: On 8eforus, well 8efore her drinker a8ilities had awoken...
So far, only Jade Bloods have been seen as Rainbow Drinkers. Later conversations between Kanaya and Porrim confirm that being a rainbow drinker indeed directly relates to having jade blood. Kanaya also stated that their caste must have developed these abilities after working in the dark birthing caverns, while Rose suggested that the ability could have been developed to scare predators away from young wigglers.
- The glow-in-the-dark skin of Rainbow Drinkers is a reference to the Twilight series, which features Vampires, whose skin gitters in the sun.
- The novels Kanaya reads also feature Shadow Droppers. The name references their ability to go out in daylight and consequently casting a shadow. It is unclear if this is another fictional creature that can withstand the sun or an alternative term for Rainbow Drinker.