When brainstorming how to retrieve the Infinity Stones from history for the Time Heist, Thor informed the Avengers of the Aether, and how it was infused in his at the time girlfriend, Jane Foster. Noting how the Aether's powers were unpredictable and different than the potential powers that could be achieved by the Reality Stone, Thor suggested that the Avengers contain its powers so one of them doesn't end up becoming its next host. They then created a device that would allow them to extract the Aether from her body.
When Thor and Rocket Raccoon traveled to Asgard in 2013 during the Second Dark Elf Conflict, Rocket made a plan for Thor to distract Foster as he injected her with the device. However, Thor left him, so Rocket had to go in solo. Rocket snuck into Foster's room, and when she woke up, Rocket crept up behind her and extracted the Aether from her body. Once he got what he came for, Rocket regrouped with Thor and they departed from the past, having succeeded in their mission.
The Aether extractor was designed by the Avengers under Thor's suggestion that they would need a certain device to extract the stone from Jane Foster's body without any repercussions. During the Theft of the Reality Stone, Rocket managed to obtain the Aether from Foster's body and returned to 2023 with the extracted Infinity Stone. The Avengers assembled the stones together and somehow managed to solidify the Aether into the Reality Stone so they could place it on the Nano-Gauntlet.