I waited until I played through Awakening to see how Leliana's absence is dealt with in game. As it really isn't, I'm free to fill in the gaps! You might want to read
these things first, if you haven't already.
As you can see my goal was to answer all the pertinent questions: Why isn't Leliana with the Warden? How did Morrigan manage to insinuate herself into the Orlesian court? What happened to all the blank vellum the party picked up?
Oof. This is getting really self-referential, isn't it? I promise I'll put the Morrigan joke away (for now).