Our purpose - Darkners' purpose - is to assist them. It's the only way we can feel truly fulfilled.
Ralsei to Lancer
The appearances of the majority of Darkners are themed around their environments and the inanimate objects they represent in the Light World. For example, Chapter 1 features Darkners resembling playing cards, games and other ephemera found in the Unused Classroom that Kris and Susie end up in after leaving the Dark World. Chapter 2's Darkners by contrast mostly take on the form of electronics and software components, reflecting the computer room setting in the Library.
Darkners themselves can be moved from one Dark World to another by having Lightners transport their Light World counterpart objects to the relevant Dark World, which forms the basis of the recruitment mechanic beginning in Chapter 2. However, if a Darkner stays in a Dark World that is inhospitable to them for too long, they eventually turn to stone until they are returned. The notable exception to these rules is Ralsei who does not turn to stone and is capable of moving between worlds off-screen, seemingly without any assistance from Lightners.
According to the Prophecy, Darkners and Lightners once lived in harmony. The Earth would be doomed to a destruction known as The Roaring if the balance of Light and Dark were to be disrupted, a phenomenon caused by an excess of Dark Fountains.
This doom can only be averted by the Delta Warriors, who will restore the balance of Light and Dark by sealing the Fountains and casting away "the Angel's Heaven". in the abandoned Castle Town surrounding the original Dark Fountain, a lonely Prince of the Dark awaited the Prophecy's other two heroes, hoping to avert the destruction of the world.
The people of the Card Kingdom remember living in harmony with the Lightners, but they now believe that the Lightners abandoned them and trapped them in a sealed realm without a purpose. Recently, a strange Knight appeared and led one of the kingdom's four Kings to rebel, annexing the realms of the three other Kings and forcing their citizens to serve him and obey his son, Lancer. Around the same time, a new Dark Fountain emerged near his Card Castle, disrupting the balance of Light and Dark, and the court jester, influenced by someone to believe that the world was only a game, was imprisoned on orders of the four Kings by the court magician, who then left the castle too.
Enraged and heartbroken by the Lightners' abandonment, King came to believe that the emergence of "holy" Dark Fountains to further disrupt the Balance would cast the world into eternal darkness instead of destroying it, allowing Darkners to take rulership and inflict suffering on Lightners. Many of his former staff, fired during his rages, were imprisoned or forced to find work elsewhere in his Dark World.
With the appearance of the prophesied heroes, the Prince of the Dark leaves Castle Town to accompany them to the second Dark Fountain. Along the way, they meet King's son, who had been ordered to stop them and who orders groups of Darkner fighters to oppose them. Despite initial friction, the party eventually reaches Card Castle and confronts King, with the battle's aftermath depending on how they treated their enemies along the way. The Lightner heroes proceed to the second Dark Fountain, where they return to their own world.
The Darkners of the Cyber World are largely on good terms with Lightners, unlike those from the unused classroom Dark World. The only possible exception is Queen, the eccentric monarch of the Dark World, led astray by the Knight's power; convinced that creating more Dark Fountains and thus Dark Worlds creates further prosperity for her subjects, not knowing the true consequences of disrupting the balance between light and dark.
In order to accomplish her mission, she plans to capture Lightners (notably Noelle Holiday), knowing that Lightners with strong determination can create Dark Fountains, much as the Knight could. She changes her mind about her plan quite quickly after learning the true nature of The Roaring from Ralsei.
- Main article: Category:Darkners
- The dialogue portraits of Darkners appear in color, as opposed to the monochrome Undertale-style dialogue portraits of Lightners.