If I was the sort to be even remotely interested in playing an origin character, it actually would be Astarion. As the PC, you could play him as introspective (although I imagine it would largely be headcanon), looking back on his past choices and what led him to where he is now. You could make him own up to it and choose to be a better person, to shed his misdeeds and be more than any depraved spawn could be, proving to himself and the world that he has done his penance and is worthy of a better life.
As an NPC companion, though, he's coded as bad and loving it. Simply put, he approves of many evil actions and disapproves of many good actions; beyond good and evil, he is a "fun-loving" agent of chaos. When he interacts with the player, he takes on an accommodating persona to match the vibes you put out, good or bad, etc. I'm hoping Larian has already considered the angle I presented for PC Astarion, where a good-aligned player could have such in-depth conversations with him to encourage some healthy introspection. The player is persistent, but doesn't push and practices what they "preach" as a good role model, but isn't a stick-in-the-mud, and maybe it finally opens his eyes. If they did this, then I absolutely could believe in him bettering himself as a person without it being a shallow arc. But he'd still be mostly neutral, lol.
I guess I just have little faith in people putting that much thought into characters. Very few games in existence allow such nuance. Fingers crossed, I guess.
