Extant was born Hank Hall, In order to save their father's life he and his borther Dawn became The servants of 2 lords, one of Order and the other of Chaos. Dove was killed by a shadow demon in Crisis on Infinite Earths. A new female Dove soon partnered with him.
During the Armaggedon 2001 story, the time-hopping villian Monarch travelled into the past and captured Hawk and Dove. After murdering Dove, He reveled that he was infact Hank Hall. This drove the current Hank Hall mad who killed his older self and took his armor for his own becomming Monarch.
After travelling into the past with Captain Atom, he confronted his old enemy Waverider and after being effected by Waveriders power he realized when Dove died her powers went to him. He used both the combined powers of Hawk and Dove to transform himself into the villian Extant. He then stole Waverider's armband and used it to travel threw time where he encountered Parallax and forged a partnership. He then laid seige to the Liner Men's stronghold Vanishing Point and then attacked and absorbed Waverider, gaining all his powers added to his own. He then killed several members of the JSA (Dr Fate, Hourman, Sandman, and The Atom). After Parallax was defeated he escaped into the time stream and discovered the Worlogog, the map of all time. He attacked and defeated Metron gaining the power of the Mobius Chair which he used to obtain the Worlogog from the new Hourman. He fused himself with the Worlogog and the power of the Mobius Chair, reaching his final form.
And that's how he became the Extant of today.