I'm sorry, I need to unload this.
I fear for the eventual re-introduction of Mr. Dark. Part of what makes his character work is that we don't actually know anything about him. Chances are any backstory or development would only diminish him and be a dissappointment for the fans.
There could be a way, however. A way to explain him and still keep his aura of darkness. A way that ties him into the setting and cements his role as Rayman's Arch-Nemesis.
We now know that Polokus' First Bad Dream, Jano, has the capacity to produce Antitoons/Darktoons. We know that The Heart of the World/The Great Protoon somehow prevents Polokus' Nightmares from manifesting within The Glade of Dreams. Because of the trouble caused by the arrival of the Nightmares, we can surmise that The Heart/Protoon either didn't exist at the time, or didn't possess the ability now associated with it. We now know that Rayman was created by the Nymphs to combat the Nightmares, so he was created some time AFTER Jano and the Nightmares had come into existance. If Rayman was created in response to Jano, it's very possible Jano found out what they were planning, and sought to prevent it. It's stated that Rayman lacks limbs because the Nymphs lost several of the Lums they had collected while chasing some Zombie Chickens. It's possible that, at the time, Jano's plan was to steal the Lums from the Nymphs to stop them from creating a being capable of bringing about his defeat in some way. When his forces failed to acquire all the Lums, Jano had to think of something else.
Created during the war with the Nightmares, Rayman most likely embarked on his first adventure shortly after being created. He likely either combated Jano directly, or somehow brought about the current condition where as long as The Cosmic Balance is maintained in The Glade of Dreams Jano and the Nightmares cannot enter it freely. But Lum-based beings like Rayman himself would be exempt from this, meaning a being made from them could go about his or her business freely without the Heart/Protoon affecting them.
Knowing that it was too late to prevent the Nymphs from carrying out their plan, Jano decided to implement a secret backup plan in case he was unable to defeat Polokus' new champion. Using The Lost Lums, Jano created a being that was the antithesis of a Hero. Rayman was created to bring peace and stop the Nightmares. Jano's Champion was created to sow chaos and free the Nightmares from their imprisonment. Rayman has his friends to help him on his adventures. His counterpart would have to be able to work alone, because anyone he could call a friend would be sealed away by the power of the Heart/Protoon, at least at first. It's possible that Jano was worried about being able to control his Anti-Rayman, and so sealed him inside some sort of magical stasis. If Jano failed and was imprisoned, the spell would eventually fade and release his secret agent when the inhabitants of the Glade least suspected it. Because he was not, technically speaking, a Nightmare of Polokus, Jano's Successor would be immune to the force keeping Darkness at bay, he would be free to assault it directly, freeing the Nightmares.
The Heir to Jano's Legacy, Mr. Dark
Much more than Bad Rayman, Mr. Dark is Rayman's opposite:
- Rayman is childish; Mr. Dark comports himself like an adult. Even his name reflects this difference.
- Similarly, Rayman's name doesn't reflect his function as a Hero; when not saving the Glade he lives his own life. Mr. Dark's name is a reflection of his function; he exists solely to promote Darkness.
- Rayman needs the support of the Nymphs in order to function as a Hero. Mr. Dark's allies are all imprisoned, so he has to be able to operate alone for long periods of time. This is shown by his strong magical ability; he can take on a Nymph in combat and win!
- Rayman is reactive, only saving the day after someone else has endangered it. Mr. Dark is proactive, seeking to instigate calamities capable of upsetting the Balance in the Glade.
- Rayman is very open; he has few to no hidden qualities. Mr. Dark is mysterious, keeping his identity and history a secret so as to keep his enemies guessing.
By keeping his form from the original game, Mr. Dark's existance as the Anti-Rayman is enhanced; because he was created from some of the Lums meant for Rayman, he is the only other being to be like Rayman in form, furthering their duality.
It would be a coincidence of mind-shattering improbabilities if this turns out to be the case, but I can't see any other backstory working as well for him. It's like The Joker
in The Dark Knight
; any explanatiojn would just dimish him, he works better as some sort of meaningless manifestation of chaos. He isn't some guy, the laws of reality meant an Anti-Batman had to form, and that's him. He just popped out of the fundament one day and set about being Batman's opposite.