You need to deal with Alexius because Fiona has no negotiation powers anymore. Magister Alexius of the Tevinter Imperium walks in with his son Felix. Something is definitely going on and just when you thought you’d never get an answer, it comes barging through the door.
You’ll meet Grand Enchanter Fiona, but oddly enough she thinks this is the first time you’ve met. Head to the Gull & Lantern tavern when you’re done exploring the settlement. You can even find Connor, son of the previous Arl of Redcliffe, down by the docks if he is still alive in your game. There are plenty of codex entries to find for quick experience gain.
Shop, accept quests by speaking to people in town, and break into houses if you can. There’s a lot to do in Redcliffe before you continue with the main quest.