Phoenix

Years later, Thanos started searching for his lost son, disguising his quest as a new mission of galactic conquest. He and his Black Order would raze planets, demanding a tribute of the heads of younglings between the ages of sixteen and twenty-two (the estimated age of his lost son), or the annihilation of its inhabitants, with his search eventually leading him to Earth.

The Inhuman king Black Bolt discovered Thanos' true intentions on Earth by using the Inhuman Codex, a device which contained all the information about Inhumans and their descendants. Using coordinates to the locations of several Inhuman tribes on Earth, the Illuminati embarked on a search for Thanos' son. Unfortunately, the Doctor Strange who found Thane in Greenland was secretly under the control of Ebony Maw (one of Thanos' lieutenants) who used his powers to make Strange forget that he had found Thanos' son.

When Thanos fought Black Bolt in Attilan, the Inhuman king detonated a Terrigen Bomb, which subjected any person with dormant Inhuman genes on Earth to Terrigenesis. Thane's powers developed from his transformation and became unleashed, killing every inhabitant of Thane's town in the process. Ebony Maw arrived and convinced Thane that he was there to help him by providing him a suit to control his new abilities. Maw then trapped Thane in a containment field, and informed Thanos about the finding of his son. Thanos arrived to Orollan and informed Thane of his plan to kill him.

As soon as the Avengers arrived to Orollan in order to defeat Thanos, Ebony Maw tested Thane by freeing him. Thane could escape, or could fight Thanos and become what he avoided his entire life. The boy agreed and embraced his true nature as the son of Thanos by fighting his father. Using the power of his right hand, Thane trapped Thanos and his last loyal general Proxima Midnight in an amber construct which left them in a state of "living death." Upon Thanos' defeat, Ebony Maw started manipulating Thane into becoming something far worse than anything Thanos could have ever dreamed; a better man than him.