What do you think would’ve happened to Baelor if it had been Maekar to die at Ashford?
It’s interesting to consider what narrative would develop across the kingdoms if it was Baelor who landed the killing blow. Maekar had to carry the title and burden of kinslayer for the rest of his life, even as king, but I wonder how much of this vitriol was because of Baelor’s great popularity, how he’d died doing such a courageous thing, and how Maekar robbed them of what surely promised to be a decent king -- and just because Maekar was far less liked. Kinslaying is obviously a very big taboo but Targeyrans have got away with worse, the trial was technically a legal place for such things to occur, and general consensus seemed to have deemed Duncan’s side as the morally “right” one by the end, and one Baelor risked much in joining (not in physical stakes due to the kingsguard by figuratively). I personally think Baelor wouldn’t have carried such a black mark in the public’s eyes, especially as just the following year he would be king and would be in a good position to quickly shift narrative. Whether he would want to is another matter (he’d probably be conflicted on it but his sense of duty would push him to).
As for a more personal fallout, I’ve spoken before about how Maekar's sons would react to Maekar’s death at Baelor’s hands, and how Baelor would just shut down emotionally after that and devote himself solely to duty. In terms of how Baelor would be treated by the wider family for it, it’s hard to say because there are so many steps leading up to the trial even happening where blame can be placed, and we know that these are relatively pragmatic Targs compared to who have come before (or King Daeron is at least). Baelor is eloquent and clever enough to explain and justify his actions leading up to it, but again, I don’t know how hard he would push this. Baelor seems to me as someone who quickly succumbs to self-flagellation over his own mistakes, and this is the worst of his life, something he would seem utterly unforgivable. The anger and blame of his family might be something he feels he is owed, something he might even push for, even subconsciously. Ultimately, I don’t see a lot of blame placed on him, or at least they wouldn’t outwardly treat him poorly for it. They all knew what Maekar was like, how he threw himself wholly into battle and welcomed Baelor to do the same, and they knew how Baelor adored him. There could be no question that Baelor did this unintentionally. And not blaming the older brother who has always looked out for all the rest vs resenting the younger hot head who was always seeking to prove himself and rarely thinks things through (bc he can rely on Baelor for clean up) is very different. (I also think Ayrseys would gladly become Baelor’s Hand.)
What I think Baelor would absolutely do is look out for Maekar’s children out of sheer guilt, grief, love, and obligation, and ironically, probably take far better care of them. Daeron would be excused from most of his duties (Baelor seemed to be pushing for this even w/ Maekar alive) and his dreams/ the treatment for them given more serious care. I’ve yet to see anything that leads me to believe this can be cured or elevated but at least he wouldn’t feel quite so miserable all the time from all that pressure Maekar was heaping on. Aerion would still be sent away but probably somewhere more controllable with better discipline and regiment where Baelor would monitor him, maybe somewhere in Dorne with one of their allies. Egg would squire Duncan, who probably would be in the kingsguard (yawn), and Daella and Rhae would come to court and be taken under Jena’s wing. Even they I don't think could truly hate him, but Baelor would feel sick every time he looked at them. Aerion could never come back to court because Baelor is so terrified of seeing Maekar's face looking back at him.
