According to the Epic of Wreckburner, the Dark Spark was created by the Fallen. The poem maintains that the Fallen took a pure soul from the Well of All Sparks and corrupted it with captured Angolmois Energy from the defeat of Unicron. The Fallen then sealed the tainted essence in a crystal sphere.
According to the Digital Vaults of Ibex, the Fallen gave this Dark Spark to General Dery, one of the early Decepticon leaders, to assist him in battle first against the Quintessons and later against the Autobots. When the Fallen disappeared, the Dark Spark was one of the few of his artifacts to remain on Cybertron, according to sources from the Autobot Hall of Records, released through the Library of New Harmonex.
While in possession of the Dark Spark, Dery was said to become a monster on the battlefield, according to Alpha Trion’s A Brief History of the Second Cybertronian War, Volume 23, Chapter 49. According to the Rust Sea Regional History (from the Imperial Archives), the Dark Spark was said to allow him to raise those that fell before him as undead warriors under his command.
Possibly apocryphal stories from The Senate Register say Dery could control Trans-Organics, drawing them from beneath Cybertron and sending them into battle on Dery’s behalf. The Library of Harmonex (accessed and archived pre-dome) says Dery went as far as levelling Iacon before losing his life to a challenge from one of his own subordinates: Gladiaron.
After challenging and killing Dery, Gladiaron took the Dark Spark as his own, according to Feature Exhibits of Polyhex. The Dark Spark was said by the Archival Research Catalog to grant him incredible speed and strength, making him the most powerful hand to hand combatant on Cybertron.
On the battlefield, The Imperial Timeline says Gladiaron was unstoppable, as he sought out the commander of any forces facing him and destroyed them personally with his own hands. No one knows the exact circumstances of his eventual defeat, but fragments from the Lost Library of Tyrest indicate one Autobot claimed the deed: Nominus Prime.
After the death of Gladiaron, Nominus Prime conquered and seized control of Cybertron. Under his rule, Cybertron was a planet full of corruption, social apartheid, and general oppression, as extensively detailed in Pyrostorm’s History of Autobot Conquest. The Dark Spark itself was never seen again, until it showed up recently in the hands of the Seacon leader Snaptrap.
Recently Snaptrap used the Dark Spark to vanish Deathsaurus. Analysis of data collected by Thunderblast and Blast Off suggests a portal was opened to an alternate universe, to which Deathsaurus was banished. Snaptrap and his Seacons have recently been mentioned by another interdimensional traveler: Negative polarity Ravage. Recommendation: Seek out this alt-Ravage for interrogation as to Snaptrap’s recent activities.