let me just say something fast then explain with detail, to solve this problem put Viviene points above Cassandera and Below Leliana. if Cass is 4 and Viv is 10 and Leliana is 11 they will elect Leliana if Cass is 0 and viv is -1 and Leliana is +10000 they will elect Cassandra. you don't have to restart.
now that you know the solution(use the nobility perk to boost viv if you have to, Cass will slightly disaprove, she is quite forgiving lol)
now let me explain.
Cassandera is a Hero , a seeker dragon hunter I don't know nobility of Nevarra people call him instrument of the maker, and she is a reformist. just listen to her "I want to do some fixes here but respect tradition" "I'm not be afraid of change but lets go back to circle of magi." "we should monitor mages but they should govern themself." these kind of talks means everything will be the same just more flexible and clerics like that... so that and her reputation makes her a winner very easily.
Now lets talk Leliana, Bard Spymaster cold blooded killer saboter assassin mean and scary. almost everyone even IronBull says he is afraid of Leliana at one point. try romancing Josephine she will threat your "well-being" very seriously if you harm Josephine! and she say it in a tune you know she mean it. 95% times the meanest option in war table is Leliana options plus she wants to just revolutionize chantry. opening priesthood to brothers 🙂) accepting qunari in chantry just imagine how far she wants to go with her changes. when she is elected she brings the elven part of chant back to song and publicly walk everywhere with HoF until she eventually even removes the marriage restriction of divines... clerics just throw her name around because of how close she was to Justinia.
There is more to her. she from day 1 knows Blackwall is not a warden never informs you, her spies never answer to inky directly just to herself, she disobey you at whim and will, threatens you. even talks down to you (if you tell her you wont support her as divine she should be like ehhh you don't matter anyway) and as soon as red lyrim magister darkspawn(forgot his name) dies she ditches inquestion and quit(go talk to her at trasspasser).
Viv , is complicated character not going to write her but power hungry wise and almost caring. if you are loyal to her she cares a lot about you..... but she is there mostly to use your influence to further herself in "the game" she is smart and can take advantage of opportunities and that's why she invites you over and joins instantly. just look whose she is married too. what a nice viper she is i love her character.
so the game is smart and tries to be realistic it does consider people personalities. since Viv never really even seen Justinia and is a mage if she is in a race with Leliana in points Leliana will be FORCED to the clerics. because declaring a mage as divine is a very hard pill to swallow for clercis even if she is a templar in heart.
summery , if you want to put Cass on sunburst throne in my opinion don't. she is the "kinder" Viviane! put Vivane herself.be good at "the game" viviene needs inky so bad to remain in power even the epilogue says inquestion is all standing between her and failure. if you want to make everything 10% better in Thedas pick Cassendera and if you want a real start over like me pick a softened Leliana as a steeled one will be just an evil unleashed on the world --- choose Briala , Keep Wardens , do it for vengeance and ally mages or conscript order and avoid encouraging cassendra to take the seat. she is a seeker let her be the super templar fighter and you have Leliana there.
p.s. if she is in relationship with an alive HoF hainv sunburst throne as well is too much for her. go with cas :P
