Tentative timeline for chapter 6:
- Susie shows Noelle the Castle Town dark world.
- Noelle learns that dark worlds are real and remembers how to create a dark fountain.
- Noelle goes home and creates a dark fountain in her home to try to heal Rudy.
- The fun gang enters the dark world, which is Ice Palace themed.
- Just when we need Ralsei's fire magic the most, they leave the party.
- Noelle joins the party as the new healer.
- Some Ice Palace sections are/can be replicated. (Trying to guess which ones and how requires more posts.)
Question: Why would Noelle, who created the dark fountain, join the team with the objective of closing it?
What happens next I don't know. If chapter 5 was the last light hearted chapter, I don't expect a funny and quotable antagonist.
Having said that, the posts on Noelle's blog do seem to point towards something appearing. Maybe the SPECIAL, over-moded, weird sound making, "left home due to happiness" creature from her Cat Petterz game. Which could be FRIEND (again) because cats, or the tail of hell because circles (Or both). Either as an antagonist or secret boss (although we already have all shadow crystals). There was a connection between Noelle and Spamton with the pipis spam email virus, and they loosely interacted in Chapter 2.
Rudy will be there, and probably Carol too. If Dess is the Knight, this would be a great moment for that to pay off, although I expect the Knight rematch to be in Chapter 7 in the bunker dark world, so it's the same in all routes and is what's foreshadowed by the ERAM fight.
I agree with almost everything on your timeline besides a few points:
1. I don't think that Noelle will make the chapter's main fountain. Rather, I believe either Carol or the Knight will (with a slight lean toward the latter).
2. I think the chapter will contain the Knight rematch. Given it took 3 chapters to fight the Knight the first time, it feels fitting for the rematch to happen after another 3. However, I think the rematch will be pushed back to chapter 7, inside the Shelter, in the Weird Route.
3. I think that Noelle's newfound dark world knowledge will instead come into play at the very end of the chapter, where she will start the Roaring in reaction to Rudy dusting.
I would also add these points to the timeline:
1. Carol will be the chapter's forefront antagonist, but she will have a darkner henchman (possibly Dess's guitar) who overthrows or backstabs her to act as the true antagonist.
2. Rudy, although present in the dark world, will be "fallen down" for the entire chapter. To Noelle and Carol's dismay, healing magic won't work on him.
3. The Knight will try kidnapping Carol.