What capture? As far as I know, she was never captured.... I think part of the problem is you're starting with an end result in mind and forcing a plot that will make that happen. It will work better if you create a situation (after getting to know the characters thoroughly and as presented in the game first), and then let game lore and the characters guide you. If you let them 'speak', your work will be far more nuanced and exciting--for you as well as for the reader. A plot doesn't have to be complicated or have super powerful characters in it to be interesting. just create a situation that they care about and see what they do.
I wrote it in the OP. And no, you have to settle the overall plot direction from the beginning and change the details for the characters or it might lead to nowhere, I've tried it before.
I did, SI is cunning and dirty, SW is strong and wanted to prove her strength. BH is cold but she had her discipline, would not betray her employer unless they betray her first or do unnecessary killings.
The problem is just about Satele Shan but we just put it away, she would sacrifice herself for her son right? Let's start from her capture.