Dark Gaia is a primordial hyper energy organism that lies beneath the surface of Sonic's World and has been in eternal conflict with Light Gaia. Together they have maintained a cycle of destruction and rebirth since the dawn of time.
When Amy Rose met Sonic the Hedgehog for the first time at Never Lake, an illustration that heavily resembled Dark Gaia (as well as Chip) could be seen on one of her tarrot cards (the same set that allegedly predicted her first meeting with Sonic), possibly fortelling of the beasts eventual awakening. (StH: #290)
Awoken Too Soon
According to Professor Pickle, Dark Gaia had a history of causing the planet to break up into fragments, not unlike the situation that resulted during shattered world crisis. Tikal indicated that the breaking of the planet following the Super Genesis Wave was an acceleration of the natural cycle, happening prior to its proper time. As a result, Light Gaia was left weakened and unprepared for the task that lay ahead of it. Additionally, portions of the creature's energy began seeping through the cracks in the planet, and some coalesced into Dark Gaia Creatures. (StH: #259, SU: #63).
After Sonic beat Dr. Eggman's Egg Dragoon, Dark Gaia finally regained its consciousness thanks to Eggman gathering its fragments with the Summoning Spire. Now strong enough on its own, it began reabsorbing its energies from across the globe, allowing to mature from its incomplete state into its "perfect form". (StH: #286, #287)
Dark Gaia is capable of exerting its essence as a corruptive, yet potent energy gas referred to as Dark Gaia Energy. This energy is capable of causing mutations at night, blocking spirits, and enhancing negative feelings. When coalescing, it can also create hostile monsters.
- Dark Gaia is the main antagonist of the game Sonic Unleashed. The storyline in which it appears in the comic is based on the story of said game.
- Dark Gaia was first referred to in StH#193, though it was not referred to by name nor was actually seen on panel. Additionally, the story in which it was referred to took place in the Another Time, Another Place universe.
- in Sonic Unleashed, Dark Gaia's essence was seen to put people in depressed moods; the comics indicate that it can also increase aggressive tendencies, and that high concentrations can lead to mutations as seen in the case of Sonic.
- Dark Gaia at Sonic News Network