In Conclusion –
Not as a systematic conclusion, but per my vague heuristics, it seems quite plausible that there’s no inconsistency between a proper libertarian conception of the will (e.g. those of Maximus & Scotus) and universal salvation (apocatastasis).
As long as we draw the necessary distinction between choosing “between” good & evil (being & nonbeing) and choosing “among” goods (on a Pareto front of equally optimal choices), along with the further distinctions of our essential & secondary natures (Scotus) and natural & gnomic willing (Maximus), apocatastasis can be conceived as sufficiently self-determinative.
Gnomic willing is what our one will, the natural will, does when epistemically-axiologically distanced, as it chooses to act or refrain from acting in accord with divine logoi, i.e. choosing or refusing participation in goodness & being, thereby forming or deforming one’s secondary nature as, in varying degrees, virtuous and/or vicious.
If we conceive our epistemic-axiological distancing in theotic terms, as our temporal journeying from image to likeness, our gnomic willing constitutes our co-creative participation in Being, beyond being, in Goodness, itself, beyond goodness. Our self-determined secondary natures, ad majorem Dei gloriam, will thereby gift us such holiness & beatitude that some souls will, indeed, outshine the sun.
I have insisted, for decades, inspired by something, per my dim recollection, that Hans Kung once suggested regarding eschatological anthropology (though I can neither cite nor recite it): that every beginning of a smile, all wholesome trivialities, every trace of human goodness, will be eternalized. Upon further reflection, consistent with those thoughts, it seems to me that every self-determined refusal to participate in goodness & being will be likewise respected, as any vicious aspects of our secondary natures transist into eternal nonbeing, as those temporal moments are essentially constituted by self-annihilations of our secondary natures.
I see no a priori reason that complete closures of each person’s epistemic-axiological distancing cannot be accomplished post-mortem, e.g. such as in instantaneous life reviews or via other such purgative vehicles, thereby eternally “fixing” our secondary natures and, definitionally, ending all gnomic willing.
If, in some unimaginable putative worst case scenario, a human person would transist into eternity with no measure of a virtuous secondary nature, no happy eternalizations, whatsoever, what might that entail?
There can be no eternal annihilation of a person’s essential nature, which will necessarily enjoy eternal being by virtue of its intrinsic goodness. That essential being can in no measure be diminished or demolished self-determinedly. No one conceives of a libertarian free will on such terms, especially those committed to the (theo)logical necessity of eternal fires & brimstone.
How, then, might we conceive this bare personal essence, bereft of a virtuous (and vicious) secondary nature? Well, following the conventional “age of reason” approach, which defines the threshold for the growth of rudimentary, self-determined secondary natures (moral & theotic), I conceive such an essential nature in terms of early childhood, as precious sacred faces, whose voices make such precious sacred sounds. And, in an eternal environs, no longer situated per an epistemic-axiological distancing, I envision those children of God & ourselves in pure delight & as wholly beloved. Now, if in holiness & beatitude, they present as tiny votive candles, thoroughly on fire with divine love, while others shine forth as this or that blazing helios, surely, that will not diminish their lovability? That others might be holier than us, O’ Lord, grant us the grace to desire it, provided we shall be as holy as you’d have us be!
What might constitute different degrees of beatitude? both of different measures of self-determined, virtuous secondary natures & of precious, sacred essential natures?
Different degrees of beatitude will be experienced commensurate with the self-determined ontological densities of each person, as measured in relative spiritual intensities (both moral & theotic) and experienced in degrees of expansive aesthetic scopes, that is in terms of the number of choices “among” eternal goods of which one has freely chosen to avail oneself. In this sense, the imago Dei will have grown in divine likeness, for, while the divine nature undergoes no change in perfection vis a vis aesthetic intensity, the divine will, esse intentionale, is ever “affected” in terms of aesthetic scope by our free, self-determined choices to participate in Being, in Goodness.
It is in this sense that I would suggest that the difference between our essential & secondary natures might roughly map to such distinctions as we’ve always recognized in terms of, for example, imperfect & perfect contrition, eros & agape, early vs later stages of Bernardian love, illuminative & unitive ways, Ignatian degrees of humility and so on.
It has always been accepted that imperfect contrition and love of self for sake of self & love of God for sake of self are sufficient. Such “enlightened” self-interest has always been sufficient for parents? I fully expect it will remain sufficient for our Heavenly Father and that it will obtain for all the requisite conditions necessary for our own eternal beatitude. For, as DBH has so compelling argued, who could enjoy an eternal existence separated from those we’ve always loved and will always love unconditionally?
Exploring the Other Side (well, one part, anyway)
continued from here
I could only ever conceive of a post-mortem annihilation of one’s vicious secondary nature, never of one’s essential nature (imago Dei), which would be held in existence b/c of its intrinsic goodness. I picture such a “mere” imago as a person of 7 or younger (not some horror!).
To be or not to be, who we really are, that is the question, as we freely choose to act in pursuit of options that we know to be good (all equally or each sufficiently so) or not to act in consideration of same.
One can act in an inconsiderate or thoughtless way, without considering the good, under some compulsion, hence exculpably, or after considering the good, sinfully, in both cases depriving one’s act and its effects of any distinctively human quality. One can, thereby, nihilate the very essence of one’s being in a de-privative act that can potentially render effects deprived of the good (privatio boni).
Habitual patterns of in/considerate acts yield our secondary natures, which can include varying degrees of both virtuous & vicious natures, hence degrees of likeness to our God, extrinsically, varying in moral & spiritual intensities, which proportionately gift expansions of freedom & aesthetic scope. Our essential nature, an imago Dei, though, remains intrinsically good.
It seems quite probable to me that every authentically free human act, participating in Goodness, itself, has an intrinsically eternal quality, that every trace of human goodness, every beginning of a smile, all wholesome trivialities, are sophianized, gifted an eternal aesthetic scope. Other acts are self-nihilations, diminishing our secondary nature’s likeness to God in varying degrees, while, intrinsically & inviolably, our essential natures remain a precious, sacred imago Dei, a durable aesthetic intensity.
We thus self-determine, in every act, how much of our secondary nature gets eternalized (as virtuous) or self-nihilated (as vicious), what degree of authenticity we freely will to realize.
My Universalist Account
What if God honored all freely refused participations in eternal goods as ordered toward our contingent being?
What if God honored all freely accepted participations in eternal goods as ordered toward our contingent being?
What if that part of the nature of our contingent being, as it was formed by such refusals of eternal goods or being, was allowed to lapse into nonbeing, precisely respecting one’s free choice?
What if that part of the nature of our contingent being, as it was formed by freely accepted eternal goods or being, was eternalized (becoming virtually essential being), precisely respecting one’s free choice?
What would transist into eternity, then, whether proleptically and/or eschatologically, would therefore be our intrinsically good essential being, with its fixed aesthetic intensity, and extrinsically good (virtuous) secondary nature with its self-determined aesthetic scope, but never one’s vicious secondary nature, lacking sufficient moral intensity & self-determinedly ordered toward nonbeing, hence annihilation.
Concepts to be Expanded:
Emergence of probability
Via transmuted experience
In individuals as secondary nature, with a diversity of specific identities & uniformity of generals (Peircean)
In societies as culture, pluralistically, in particular religions & universal presence
Mediated or not, pneumatologically
Expressing or not, Maximian logoi
Scotus locates the will in efficient causation. For many, this represents a conceptual relocation from the formal.
Conceiving the free will as efficient cause (in limited potency to material) implicates a volition that determines only WHETHER one exercises (or refrains therefrom) one’s will but not to WHAT it chooses, i.e. it must not refer to why this or that is chosen but only to why the will wills at all, because it does remain free not to act.
As such, the will refers to the sole rational potency, never acting without the intellect, which is co-causally operative (in bringing the Maximian logoi to bear) even though not finally determinative.
The will determines neither the act of existence in potency to essence nor the formal generically determinative act in potency to one’s final cause, which makes a human existent what one truly is, e.g. a human person, the symbolic species, an imago Dei, a beloved child of God, a sister of Jesus, a brother of the Cosmos.
Taken seriously, this has enormous soteriological and sophiological implications, which is to say, regarding redemption, justification & sanctification, i.e. intiation into communion, adoption into the Kingdom, on one hand, and, on the other, beatitude & glorification, i.e. ascetically & mystically or theotically, further establishing the Kingdom via communal collaboration.
In my view, Scotus would worry about the risk of any full blown liberty of indifference , i.e. including not just one’s aesthetic scope or efficient acts in limited potency to divine logoi, materially, but also, vis a vis aesthetic intensity (ontological density), existential acts (self-annihilation) in limited potency to divine logoi, essentially, as well as formal acts (generic self-determination) in limited potency to divine logoi, finally (as if we could become other than what we already are, what C.S. Lewis might call a “dismantling of humanity”). This amounts to what M. M. Adams would call a low doctrine of human agency , although I am not wholly familiar with her precise formulation and how it might comport with my own, above.
Any such exercise and actualization of rationality makes one’s efficient acts good and increases the being of the Kingdom, ecclesiologically, both proleptically & eschatologically. But does that also increase one’s own being, intrinsically, as per a Thomistic metaethic, per se changing one’s esse naturale per a generic determination? 
Or does it only change, per an agential extrinsic denomination, one’s esse intentionale?
Does moral evil frustrate an increase in the being of one’s esse naturale, even to the point of its full diminishment, so to speak undoing one’s intiation into communion and adoption into the Kingdom, denying one’s very aesthetic intensity & ontological density?
Rather, might it frustrate an increase in being only vis a vis one’s esse intentionale, foregoing further communal collaboration in the Kingdom, restricting one’s aesthetic scope, limiting one’s ecclesiological participation, as one neglects spiritual exercises and practices of presence? 
I’m not suggesting my anthropological categories & applications measure up with anthropological rigor or even capture the points of disagreement between, for example, Eleonore Stump & Marilyn M. Adams. Even if they amount to an ahistorical, eisegetic account of Aquinas & Scotus, though, perhaps they still have some normative integrity all their own?
If stable dispositions, derived from habitual spiritual exercices and practices of presence, to act in accordance with or contrary to one’s nature, i.e. virtues or vice, do produce second natures, whether virtuous or vicious, do those ontologically negate or just phenomenologically mask our primal human nature, hide the imago Dei?
In my view, our primal being and goodness is both unalienable, due to divine esse intentionale, & inalienable, not a capacity of determinate esse intentionale.
Eternally, are we dealt with in accordance with both or either of our natures, primary &/or secondary, however one conceives these volitional loci, as esse naturale or intentionale?
If the goodness of our being is thus light, will our existence in Hell thereby be unbearable?
Let’s consider Hart:
[T]he wrathful soul experiences the transfiguring and deifying fire of love not as bliss but as chastisement and despair. 
Does not this refer to the transformative & theotic dynamisms that I addressed, above. Will not those dynamisms cease post-mortem or in some eschatological closure of epistemic distance, such as in a particular judgment & life review? Hart doesn’t take this into account, when describing the tortures of hell, but only because he otherwise ultimately rejects an infernalist stance, not inconsistent with Bulgakov’s surmise that those dynamisms might continue post-mortem, finally rejecting eternal torment as a moral absurdity.
So, if those dynamisms terminate post-mortem, wouldn’t we necessarily only be dealt with in accordance with our primary nature, which would comport with Maximian being, eternal being and well-being? Or, if also our secondary nature, only that level of goodness & being which emerged per Maximian logoi, never otherwise instantiating a privatio boni, which have no ontological reality?
Might ill-being only ever be a transitory, purgative state? Or even a misconstrual of an eternal esse intentionale, which remains volitionally indifferent to any aesthetic scope, beyond its original endowment, not inconsistent with a Scotistic free will, located in efficient not telic causes?
A post-mortem will that’s closed all epistemic & axiological distances and has been purged of any residual vicious secondary nature could only refrain from determining among the goods of an enhanced aesthetic scope, choosing not to grow one’s spiritual intensity. It would no longer be able to otherwise act inconsiderate of goods pertaining to temporal exigencies, due to having none, so, would no longer be able to sin, no longer able to vary its moral intensity.
Bishop Barron  writes: If there are any people in Hell (and the church has never obliged us to believe that any human is in that state), they are there, not because God capriciously “sent” them, but because they absolutely insist on not joining in the party.
This isn’t wholly inconsistent with the view of volitional indifference to a self-constrained aesthetic scope, but, again, what of my point that human volition is not otherwise constituted by self-constraints regarding aesthetic intensity (ontological density), existentially or generically, regarding THAT one is or WHAT one primally is (whatever one believes regarding self-constructed secondary natures)?
How, then, would we psychologize that eternal disposition? I’m asking for a friend, who’s a social wallflower, who prefers to watch the mirrorball & swirling dervishes beneath, who doesn’t mind others coming over to sit in silent presence (90% is showing up, only 10% is dancing, perichoretically or otherwise?), while they keep the finger sandwiches & beers coming. One person’s modus ponens is another’s modus tollens?
As John O’Brien observers: Concerning the detailed specific nature of hell … the Catholic Church has defined nothing. … It is useless to speculate about its true nature, and more sensible to confess our ignorance in a question that evidently exceeds human understanding. 
Fr Richard Rohr writes: To be frank, I think that perhaps no single belief has done more to undercut the spiritual journey of more Western people than the belief that God could be an eternal torturer of people who do not like him or disobey him. And this after Jesus exemplified and taught us to love our enemies and forgive offenses 70 x 7 times! The very idea of Hell (with a capital ‘H’), as Jon Sweeney explains in this magnificent book, constructs a very toxic and fear-based universe, starting at its very center and ground. Hatred, exclusion, and mistreatment of enemies is legitimated all the way down the chain of command.” 
Jon Sweeney writes: “Ultimately, I choose not Dante’s vengeful, predatory God who is anxious to tally faults, to reward and to punish. Instead I choose the God who creates and sustains us, who is incarnate and wants to be among us, and the God who inspires and comforts us. That God is the real one, the one I have come to know and understand, and that God has nothing to do with the medieval Hell.” 
Following Scotus, I intuit that no eternally self-constrained aesthetic intensity is possible, neither existentially (THAT) nor generically (WHAT).
And with Rohr & Sweeney, I’ll simply insist, apophatically, on what an eternally self-constrained aesthetic scope simply must NOT be like.
Then, with O’Brien, I’ll confess ignorance, kataphatically.
 MM Adams re Scotus’ concerns re liberty of indifference, as she cites Duns Scotus, God and Creatures: The Quodlibetal Questions, translated with introduction, notes and glossary by Felix Alluntis, O.F.M., and Allan B. Wolter, O.F.M. (Washington, D.C.: The Catholic University of America Press, 1975), q.16, art. Il, 377-79·
 ibid The Problem of Hell by Marilyn M. Adams
 Dante’s Hell, Aquinas’s Moral Theory, and Love of God, Eleonore Stump, Canadian Journal of Philosophy 16 (2):181-198 (1986)
 When God created us in the divine image, God intended us to be cocreators and participate in God’s plan. Hell may not be a literal burning fire, but does that mean it doesn’t exist?by Kevin P. Considine
 The Doors of the Sea: Where Was God in the Tsunami? By David B. Hart
 Bishop Barron
 John Anthony O’Brien, The Faith of Millions: The Credentials of the Catholic Religion, pp. 19–20
 from the Foreward to Dante, The Bible, and Eternal Torment by Jon M. Sweeney
 Sweeney ibid