Just a little late for the discussion last month, but I wanted to add my bit. I do get aggravated by mistakes and misinformation within a story, whether in a book or a game or a film. After all if one writes a story, one should be expected to keep it straight.
Fiona cannot be Alistair's mother. Apart from the story in DA:O, it is in black on white in the book The World of Thedas. The chronological section at the bottom of the pages states that Alistair was born in 9:10; but Maric only went to the Deep Roads with Fiona in 9:14. That means Fiona's son would have been only 15 when the 5th Blight started.
I did like the idea when I read The Calling; not only Alistair being a bastard but also that his mother was everything everybody despises: a mage and an elf. Imagine the uproar if it were known once he was king; the political intrigues it would add to a possible new plot if Bioware considered prolonging this particular character's story. But perhaps they have done as much as they think commercially viable with the comic books. Also it added gravitas to Maric as a character, instead of the air headed monarch who could not sit straight in his throne and could not keep it in his pants; much like his first son Cailan (as per Anora's confession in DA:O).
Now, there should be another son of Maric somewhere, who would be 26 at the time of the Inquisition. Perhaps to be added to a new game/story in the future? After all the idea of the power of dragon blood in the Theirin line is quite interesting, add a bit of magic and voila! quite the powerful character.
I make no apology for having all the books. I find Dragon Age story very engaging. I understand some people think it is unfair to expect gamers to also buy the books in order to flesh out facts, but this appears to be the case of a story for a game that surprised with its potential. After all, people who like fantasy (like me) are used to books or tv shows (i.e. Game of Thrones) in series; and we do not really care which forms it takes to develop it providing it does not fall into absurdity.