Clement of Alexandria (150-215 A.D.)
"So he saves all; but some he converts by penalties, others who follow him of their own will, and in accordance with the worthiness of his honor, that every knee may be bent to him of celestial, terrestrial and infernal things (Phil. 2:10), that is angels, men, and souls who before his advent migrated from this mortal life."
--The Stromata (also known as Miscellanies), specifically in Book VII, Chapter 2.
And
"For all things are ordered both universally and in particular by the Lord of the universe, with a view to the salvation of the universe. But needful corrections, by the goodness of the great, overseeing judge, through the attendant angels, through various prior judgments, through the final judgment, compel even those who have become more callous to repent."
--Book VII, Chapter 12 of the Stromata (also known as the Miscellanies.)
Origen
"We think that the goodness of God, through the mediation of Christ, will bring all creatures to one and the same end."
--Origen, De Principiis I.6.1-3
Note 1: Origen's rehabilitation appears to be a moral obligation owed to the man who has been treated so unfairly by history.
--Fr. Waclaw Hryniewicz, The Challenge of Our Hope: Christian Faith in Dialogue (Polish Philosophical Studies, VII) pg. 56.
Note 2: The following comment is from a 6th century non-Christian (neo-Platonist) Philosopher, and would appear of relevance to how the Greek words aionian, aionios, and aionas (commonly translated eternal or everlasting) were used and understood in the Pratrasic era.
"Do not suppose that the soul is punished for endless eons (apeirou aionas) in Tartarus. Very properly, the soul is not punished to gratify the revenge of the divinity, but for the sake of healing. But we say that the soul is punished for an aionion period (aionios) calling its life and its allotted period of punishment, its aeon."
--Olnmpiodorus the Younger (AD 550)