How can Fionia be a Mary Sue? She's lead a brutal hard life that has ended up anything but peachy. And shes hardly the most powerful mage.
If anyones a Mary Sue its the Warden. How exactly did we stop a blight in about a year when most take decades to beat if not more?
Too much suffering so that you pity her is a common trait among Mary Sues. You can look at a Mary Sue test to find out.
I haven’t read the books, but reading her wiki description, but her character seems written as creator's pet, who tries to come off as somehow really unique and likeable to all, but instead it comes off as irritatingly boring. (Like Tallis)
An elf with a troubled past who ironically becomes the lover of Maric? Okay. But on top of that being Alistair’s mother, getting the only get-out-of-free jail card from the calling, and then being promoted to grand enchanter, and now has taken in part of shaping Thedas’ current state?
Meh.
(Also you can make a non-Mary Sue warden. You’ve just got to have the balls to make mistakes and bad decisions on purpose, force characters out of your party, and romance no one if need be.)