I've made a quick guide for all the Discussion Topics you can find in the demo so far. Feel free to use it for future replays! Let me know if I've missed any, I haven't updated my game yet.
Keep in mind that Fia is at the Side Garden during the first exploration phase, so you shouldnt explore this area unless you've gathered all the topics you can discuss with her. Arshem however, won't spawn until the second exploration phase. You can find him in the Courtyard, leaning against a wall.
-Curse Runes: You automatically learn this one during Dietrich's class.
I- Topics you can learn during the first exploration phase (Ink for Inkwell quest):
• Library :
- Soulmates: Click on the scroll encased in glass to your right, the one in front of the bookcases.
- Vampire Kingdom: Behind the student who's sitting at the table you'll find a tiny bookcase with two scrolls on it. Click on these scrolls to see the world map and learn about the Vampire Kingdom.
- How to make blood pops and mixed blood: Press the "move" button to your right. You'll see a student complaining about the school uniform. Click on the bookshelf that's behind them.
• Mrs Edna's Lab:
- The Blood Moon: Click on the Armillary Sphere.
• Principal's Office:
- Whispering Globe: You learn it after you've touched the globe.
• Courtyard:
- Leeches: Student sitting near the courtyard's entrance.
• Fountain:
- Choir: The two girls walking by the fountain. [Can be discussed with Fia later]
• Archery field:
- Arshem's mother: The three students sitting at the table. [Can be discussed with Arshem later]
• Arena:
- Drakmar Witch: Speak to Diana Sharom and accept to share a few stories with her to learn this topic. [Can be discussed with both Fia and Arshem later]
• Uppergarden:
- Jellyfish: Talk to a student there.
• Shops:
- Inkwell Drama: The two students walking by the bench.
II- Topics you can learn during Thane's night event:
- Choose "Want to share mine" [Unlocks the "Ask Thane" option with Arshem at the Mess Hall]
III- Topics you can learn during the second exploration phase (Missing Cat quest)
• Fountain:
- Dream Eaters: Student going down the stairs.
• Library:
- Not really a discussion topic but if you tell Fia that Quill's looking for the cat aswell, she's going to give you some ingredients to craft cat food.