I actually wanna make the same question you did to me. I was wondering your characters positioning in the Halamshiral decision, more specifically about Briala too!
Spiridon Lavellan: at the time of their meeting in the Winter Palace, he has no opinion on Briala. He was not briefed on the fact that Briala and Celene used to be lovers, but he was educated on Celene burning Halamshiral.
There is one thing on Spiridon’s mind: establish temporary peace. Choosing Briala over others would’ve been fanning the revolution of the elves, and also a loss for him: how long does Briala think she can rule through Gaspard before it becomes a common knowledge just who is pulling the strings and with whose support.
And how long before the nobles of Orlais with their own small armies march against alienages everywhere, hang Gaspard and Briala and pull their support of the Inquisition who they now view as a co-conspirator of further unrest.
Briala would simply be too vulnerable - too many secrets that tie her to Celene. She has her spy network, but no trained armies to protect alienages should the nobles revolt against the puppet emperor or the empress who sleeps with the enemy.
Still, there’s worth in Briala’s spy network, hence why he obtains information on all three, Celene, Briala and Gaspard, and forces them to work together, at least until Corypheus is dead, after which they can eat each other alive for all Spiridon cares, because it’s not his problem anymore.
He does admire the balls on her though. Vulnerable from each side, including her own side, and yet she made her play. Gotta respect the sheer insanity of it. That’s what’s exciting about politics: they’re all fucking insane. He loves it.
Lea Surana: Briala is competition, but Briala’s spies sell plenty of information to Lea. He’’s quite happy that Briala survived and was forcibly incorporated into the leadership of Orlais. Much better an outcome than her execution. He now has more eyes into the top tier of Orlais, and he has a keen idea of the movements of Briala’s forces. That’s what you get when you become a public figure: your movements become visible. You get scrutiny. And you get tattletales in your ranks that will happily sell you out to a shadow broker. You get eyes in the Empress’ bedroom, and eyes on the back of the Dread Wolf.