Eons before the founding of the Final Empire, Preservation and Ruin worked together to create life. Preservation convinced Ruin to help him create sentient life, which would contain a tiny bit more Preservation than Ruin. The terms of the deal stated that Ruin would eventually destroy all life—as the population expanded, the gap between the two would widen and Preservation would grow progressively weaker. However, Preservation sacrificed his mind to bind Ruin's consciousness into a prison, violating their agreement. Doing so separated Ruin's consciousness from his body, the metal Atium. The Lord Ruler was aware of Ruin and that atium was Ruin's body.
Ruin was unable to affect the world directly. However, he was clever and found ways to influence the world indirectly. He was able to change text and images not inscribed in Allomantic metals.
Hemalurgy is of Ruin; it takes existing attributes and transfers it in a reduced form to another. This allowed Ruin to influence anyone with a hemalurgic spike; more or stronger spikes gave him greater influence over the person. His influence also grew the longer someone bore a spike.
Ruin could easily influence creatures with Hemalurgic spikes in them. He had to concentrate on a particular individual to control them; the amount of concentration required was dependent upon the amount of metal in their body. Creatures with a great deal of metal in their body, such as Steel Inquisitors, were almost under complete control of Ruin, while those with fewer spikes were harder to control. Ruin could also directly control the Koloss, whose minds were very weak. Ruin was also able to control the kandra, who bore two spikes each, though the Lord Ruler created them with a failsafe to circumvent his power. People pierced with single pieces of metal (like Vin, Spook, and Zane) could not be directly controlled. Instead, Ruin could appear as a voice or an image in their mind, nudging their thoughts in the directions he wanted. In some cases, others pierced by metal could see the image.
The Final Empire
It is revealed that Ruin was the one spreading the rumor about the Eleventh Metal to Kelsier, which ultimately gave Vin the clue needed to defeat the Lord Ruler.
Mistborn: Secret History
Following his death at the hands of the Lord Ruler, Kelsier decides to stay in the Cognitive Realm and successfully resists the pull of the Beyond. After Preservation traps him in the Well of Ascension, Kelsier gradually becomes aware of Ruin. He soon realizes Ruin is working to destroy Scadrial and collaborates with Preservation to foil Ruins's plans. He is freed from the Well when Ruin is freed.
The Well of Ascension
When Vin releases the power of the Well of Ascension, the prison around Ruin is broken and he is released into the world.
The Hero of Ages
- The Hero of Ages, chapter 79.
- The Hero of Ages, chapter 80, epigraph.
- The Hero of Ages, chapter 58. Quellion sees the image of Kelsier which Ruin uses to communicate with Spook.
- Mistborn: Secret History, part 1, chapter 1.
- Mistborn: Secret History, part 2, chapter 1.
- Mistborn: Secret History, part 2, chapter 3.
- The Well of Ascension, chapter 58.
- The Hero of Ages, chapter 81.
- The Hero of Ages, chapter 82.
- The Way of Kings, chapter 18, High Prince of War, epigraph.
- The Hero of Ages, chapter 1, epigraph.