*SPOILERS*
No, she's always mean and nasty.
The only thing you have control over, is how you respond to Alistair after the event.
You can talk him down, being a friend... or you can basically tell him to man up.
If you're friendly about it... he'll cheer up after a bit, and be the same Alistair as always.
(This makes it harder to persuade him for a certain choice at the end of the game).
If you tell him to man up, explaining that that's how the world works, with everyone out for themselves... he'll get his hardened personality. He'll stop joking around, and be all straight faced and serious (and boring as hell honestly).
(This makes the endgame choice easier for him... and also lets you have a threesome with him).
You can't spell "ignorance" without IGN.