Playing through a second time now and just realized that Wynne is at Ostragar and then appears at the Circle of Mages Tower later in the game when you go there. How did she survive if everyone at Ostagar was wiped out? I don't recall running into any other characters later in the game.
Although I don't remember Wynne's story let me note that definitely not everyone at Ostagar was wiped out. A lot of people obviously survived - specifically those who where under Loghain's command, and that should have been a considerable amount.
If you talk to Flemeth then she explains to you that there are other survivors of the battle that she left to fend for themselves and find their own way to safety, I assume Wynne was one of these - especially if you get to know her a bit and unlock her story.
There seems to be some confusion about Wynne. As I understood her story...
Spoliers: Spoiler
... she survived Ostagar just fine. She'd been watched by a good spirit / demon for her entire life, but she didn't get inhabited by one until Uldred tried to take over the Circle Tower. That's when she "died."
SWC
Sir Edmund:"Should you obey the lord who asks you to put a village of innocents to the torch? Is that chivalrous? Is it noble?" Me:"It's a great way to get promoted, I know that much."
I think that Wynne is one of the most masterfully crafted NPC's in this game.
huge SPOILERS Spoiler
During the course of the entire game the player is listening to her complaining about how much little time she has left and thinks that it is simply because she is an old woman living her last adventure, but it is later revealed that she was being watched over by a benevolent spirit of the Fade for her entire life, and she propably owes her innate magical ability to it. When the blood mages plot with Loghain to destroy the Circle Wynne dies(!) but she is being brought back to life by her guardian angel! That is not a necromantic transaction however, the spirit grants her only a limited amount of time in order to help the Grey Warden, that is why she keeps on telling that her time is running out! Of-course there is a little controversy here with Shale since she is obvioulsy being granted some extra time( after the end of the adventure) to escort ther(Shale) to Minrathus in order to turn Shale back to a...mortal form.
"I know you believe you understand what you think I said, but I am not sure you realize that what you heard is not what I meant. " Oscar Wilde
