The show features female characters, primarily Reggie, who engage in numerous fantastical battles within the world of Endless. However, their victories are consistently achieved through the use of unique, reality-bending powers derived from imagination, rather than conventional skill, strength, or martial arts. These powers fall under the exclusion criteria for superpowers.

Twelve Forever is an original animated series. All characters were created for this specific production and do not have prior canonical gender establishments from source material or previous installments to be swapped from.

The characters in "Twelve Forever" were consistently depicted with the same racial identities from their initial appearance in the 2015 pilot through the 2019 series. There is no prior source material establishing different racial portrayals for these characters.