Okay, fine, I'll talk about Justice/Vengeance. Some spoiler adjacent things included in this post for veilguard and other DA games.
Anders is convinced he ruined Justice by their joining, and I completely disagree. In the Fade, everything is fluid, changeable, and malleable. We know from DAtV and DAI that spirits can be "twisted against their purpose" and change from their "positive" aspect into their "negative" counterpart. I think there's more to this.
When we meet Mythal in the Crossroads, even though this is her "Retribution" manifestation, we can still impress her enough for her to show her Benevolent side. In my opinion, this hints that changing the states between the "good" and "bad" sides to spirits in dragon age is fluid just like the nature of the Fade itself, and easily done in their home environment. The lines between Determination and Spite, Justice and Vengeance, Wisdom and Pride are extremely blurry, and I think that in the Fade, those aspects can be easily flipped between.
In Crestwood in DAI, we meet a spirit extremely unhappy with the rigidity of the world outside the Fade, with things not bending to their will becoming incredibly frustrating. I am convinced that this rigidity of the waking world is what makes switching states for spirits nearly impossible, almost locking them in either the spirit (good) or demonic (bad) manifestation of their aspect. This rigidity in itself IS what "corrupts" good spirits.
When Justice is first ejected from the Fade, he probably is in his more vengeful state of mind - chased out of his home, with no way back. I believe that the second he crossed over, he became somewhat locked in that partially demonic manifestation. Firstly, his personal quest in DAO is literally to take vengeance on whoever killed Kristoff. This is no Justice. Furthermore, he expresses a wish - normally, spirits should not have wants, yet he asks the Warden Commander for a lyrium ring. Spirits should also not be possessing anybody, that is the domain of demons. When Cole comes over from the Fade in his Compassionate state, he does not possess the body of the original Cole, he makes himself manifest in his image instead. Justice, however, chooses to possess both Kristoff's body and later Anders.
All in all, I believe Anders had little to do with Justice's corruption into Vengeance, Justice was lost to it the second he crossed the veil. Perhaps in time, he may have learned to tune into his more "just" self - like Spite can when he agrees on a plan with Lucanis to save Caterina, which has not an ounce of spite to it, only Determination. But being stuck in a city built on blood magic, in the worst slum of said city, surrounded by everyday injustices and Anders' own need to avenge Karl and other mages, there was no chance for him to learn to cope better in this ugly, rigid world.
DAO Baroness, when I catch you... She ruined my boys :(
