It seems to me that Celene and Briala are a lot alike, both in the obvious good ways, and in the slightly less obvious (but extremely important) bad ways. The only things that Celene cares about are power, and Briala. The only things Briala cares about are elves, and Celene. Both have caused the unnecessary deaths of countless innocent people (Briala much moreso even than Celene since her plan is apparently to orchestrate the deaths of so many humans that somehow elves will be able to one day take over the whole country, which of course will never happen but will certainly result in a LOT of deaths) . I think Celene and Briala will get back together one day, and I hope that we can help make that happen, naturally their getting back together would be one of the most fun and satisfying parts of the game. Each one has betrayed the other in unfathomably huge ways, but they still love each other, and clearly if a love can withstand that much killing and betrayal from each side, it can withstand anything, and that's putting it mildly
. Celene cost Briana her parents, Briala cost Celene an uncontested throne. And if you think about it, I don't think Briala even did it because of her parents, or the elves in that city that Celene burned just to make herself look good (which obviously backfired in a huge way since it resulted in her being ambushed and almost killed right afterward) . I think Briala ultimately betrayed Celene out of jealousy, because she mistakenly believed Celene cared more about Michel than her, due to the way events transpired in that final battle (for which we never got an explanation, but clearly Celene loved only Briala, so there must've been an easy explanation that was just never given, maybe they'll address that in the game) . Once Briala calms down, has killed enough humans to satisfy herself, etc. we as the Inquisition put a stop to the civil war, and Celene shows her that she still loves her and only her, they'll get back together. Whether that's as co-leaders of Orlais or as private citizens is the only question, but if we can choose I'd try to make the first one happen, Celene and Briala ruling Orlais would be the ideal scenario. Hopefully Briala can stop Celene from causing the deaths of anymore elves, and Celene would stop Briala from causing the deaths of anymore humans, and they could instead rule wisely and peacefully. A true happy ending indeed!