Reality Stone

"Sire, the Aether, shall we destroy it?" "If only we could, but its power is too great. Bury it deep. Somewhere no one will ever find it."

- Einherjar and Bor

The Aether (pronounced ēTHər) is the remnant of a singularity that has existed since before the universe began and it is one of the Infinity Stones. A force of ancient and catastrophic power, the Aether has the potential to transform the entire universe. This "stone" is unique since it is in the form of a dark, red, viscous liquid, rather than a literal stone, like the other five. However, evidence from the Collector's Museum, suggests the Aether may not have always been this way and may have originally been a stone similar to the others. It is currently located in the Collector's Museum.

Origin
The Aether is a remnant of one of the six singularities which existed before the universe. After the universe came into existence, four cosmic beings known as the Cosmic Entities forged the energies of these singularities into six immensely powerful objects called the Infinity Stones. The Aether is unique in that instead of taking the form of a stone or solid object, it appears in the form of a flowing liquid or mist.

Unification
Before the Dark Elves had possession of the Aether, the stone was used in conjunction with the other five stones by six cosmic beings who linked themselves together, each with one stone. However, the effects were short-lived, as the energy of the stones disintegrated all six beings after a few moments.

The First Attempt
The Aether was used prominently by the Dark Elves of Svartalfheim, in particular, by their leader Malekith.

Every five-thousand years, a cosmic event called the Convergence causes the Nine Realms to become aligned, and in 2987 BC, Malekith planned to use this event and release the Aether to destroy the Nine Realms. The Asgardians intervened and took the Aether from the Dark Elves by force, watching as the race was apparently decimated in battle. Bor then had the Aether hidden away where none could find it, and over the following five millennia, its story faded from known history.

The Second Attempt
"The Aether cannot be destroyed!"

- Malekith

In 2013, near the beginning of the Convergence, a portal opened up to where the Aether was located; Jane Foster happened to walk through this portal and through curiosity made contact with it, causing it to become active and infest Jane's body, using her as a sort of host. After arriving back on Earth, Jane exhibited an immensely powerful energy projection just by being touched on the arm, and was taken to Asgard by a concerned Thor where the Aether was discovered by Odin. During this time, Malekith had sensed the Aether's activity and attempted to retrieve it by attacking Asgard. In the end, through the sacrifice of Frigga, Malekith and his army left before he could obtain the Aether.

Later though, when access to the Bifrost Bridge had been restricted, Thor, with a dying Jane, got Loki to get them through a hidden passageway to Svartalfheim. After getting there, they confronted Malekith and through various circumstances, he drew the Aether out of Jane and into himself and left the planet. Both parties then arrive on Earth, where Malekith uses the Aether to battle Thor across worlds during the Convergence until eventually Malekith is killed. Afterward, the Asgardians were able to contain the Aether in a hand-held container, which was later given to the Collector for safe keeping.

Aether Energy
"What I could do with the power that flows through those veins."

- Loki

The Aether converts matter to dark matter, and seeks out host bodies in order to draw strength from their life force thereby sapping them of energy in a process that would inevitably prove fatal. As used by Malekith, the only one who fully understood its capabilities, it was capable of creating tendrils of itself to strike out at opponents, or even regenerating lost limbs, along with creating a tornado of Aether energy. Whilst bonded to a strong host, Malekith, the Aether greatly enhanced his physical strength and durability thereby allowing to fight Thor on a reasonably even basis. On its own, the Aether is capable of sending out pulses of power that can throw back any who it deems a threat to itself. The Dark Elves and Malekith appeared to have a connection to Aether in that it awoke them from hibernation when the Aether was used again and Malekith could sense the Aether's location.