Child-That-Was-Taken

Box believed that vampyres were usually motivated by their quest of "seeking the Child-That-Was-Taken". (PROSE: Out of the Box)

Behind the scenes
Aristide Twain, who wrote Out of the Box, suggested on Tumblr that the mention of the Child-That-Was-Taken in the story could be interpreted as a reference to the preexisting fanon idea that the Timeless Child, the source of regeneration according to The Timeless Children, may have been an Yssgaroth before being "taken" by Tecteun, and that Tecteun's abduction of the Child may have been the secret of the Eternal War. However, Twain added the statement that "if you’d rather believe the Child-That-Was-Taken is something else entirely, who am I to stop you?".