I don't think Alistair is that young. My husband is 40, and he still talks and acts a lot like Alistair (though not publicly

). For me it seems fairly reasonable that Alistair is older than Cailan, I mean wasn't Maric supposed to be so in love with Rowan that he wouldn't have had an affair with a maid while married to her? Just something I've read from these forums though, haven't yet had the time to read the books. So I'd say if Cailan is around 21-25, then Alistair would be at least 25-29 or something? And in real life, men of that age don't usually behave so grown up at all, either

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What comes to our world's medieval period, I think DAO is kind of modernized version, as usually all of the fantasy genre is. In the real medieval era, people (especially the noble) could get engaged when they were born, and moved to live (especially women) to their future husband's family in an early age. They also could get married at the age of 12. It wasn't unheard of to marry a girl of 12-14 to a much older man. And love usually played no role in the marriage, it was more about the agreement done by the parents and relatives to gain favours, money and allies. So I think in DAO this isn't the case.
What comes to Morrigan, well she wears heavy make-up, which usually always makes a woman look older than what they are, and Leliana on the other hand wears little make-up. So Morrigan could be anywhere between 20-28, but I'd say she is more likely around 22-25. But who knows, she could even be 30, but in the lack of life experience, because it's the experience that makes us mature, not the years.
And the dog, well, I'd say he's about 4-5 years, since dogs build like that mature slowly into their full muscular mass

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