For two long years younger Asgardian prince Loki has been trapped on a floating plain being held captive by a faceless creature working for Thanos, after the battle with Thor on the bridge Loki ended up here and right away he knew who Loki was. Knew what darkness the prince held inside of him, the strength and magical skills perfect for carrying out a mission to retrieve the Tesseract from the humans and create chaos for them. Even though Loki was angry and the thought of getting revenge on his brother by taking over the realm he was sworn to protect seemed good, more than good he couldn't face the fact that many lives would be destroyed. That being said they were not happy with the prince's defiance, so another was sent instead, a rogue Asgardian banished for treason. He had no issues with carrying out the act.
While that was happening on Earth Loki was subjected to pure mental and physical torture, Loki wasn't sure how much longer he could take his mind and body completely broken. As time went one he wasn't even sure what day it was or how long it's been since he was there, the plain was dark and damp and the voice of his captor was something out of a nightmare. Loki was starving, he couldn't remember the last time he ate anything and was surprised he was lasting this long without any real form of nourishment.
When all was said and done and the Avengers stopped the rogue Asgardian and saved the earth the floating plane which Loki was held on was abandoned leaving the prince to die, Loki was chained to a stone slab waiting to die. He wasn't expecting to be rescued but soon his prayers would be answered, when Thor would return to Asgard and the bridge finally completed he was informed by Heimdal of Loki's whereabouts. The gatekeeper stressed that Loki needed to be found as soon as possible as his condition was dire.