IIRC = if I read correctly
Alright, finally I understand the hypnosis and treachery part. Thank you for your patience with my lack of comprehension. As long as Thuringwethil doesn't have the power to make him do things, then she can't use him after he's exiled, especially if she can't even find him.
Annael will not be in Doriath. He is one of the Falathrim who moves to the north after the arrival of the Noldor. We don't have all the details finalized, but he's one of Círdan's people at the beginning of Season 4, and he would then be somewhere in the north (Dorthonion, Mithrim, Nevrast, Hithlum) when he returns from capture. He does *not* live in Doriath (though he may visit there at some point in the story, before or after his capture). I suppose someone might prefer for him to be an elf of Doriath who came along with Celeborn and did not return with Beleg, so he's been on the ships but isn't Falathrim. Alternatively...he's been on the ships and he's Falathrim
We need to try to tell a story of Sindar immigrating to Mithrim/Hithlum and creating communities there, with Annael among them. It would only make sense for him to go to the woods of Mithrim if he was previously part of a Sindarin community actually living in Hithlum or Mithrim.
Eventually, Annael transitions from being a solitary hermit to being the leader of a small hidden community of Sindar elves (presumably, those fleeing other settlements for their own reasons).
Likewise, these people could only be survivors of existing Sindarin communities in Mithrim/Hithlum, destroyed in the Nirnaeth. If they were from communities farther south, then of course they'd end up living in the woods in West Beleriand or fleeing to the Havens, not fleeing
into a place controlled by Elf-hating Easterlings.
But my fear is that the Execs are going to veto it. Corey has repeatedly stated his opposition to the existence of any Sindarin communities in the north, especially before Annael's capture, most recently in Session 8. We all know that Mithrim Sindar won't ruin the story, but Corey thinks they will. Likewise, if we don't want Celeborn to betray Galadriel we have to somehow persuade the Execs to let Celeborn keep his silence.
I know we haven't established all the details yet - how will Annael get captured? Will he try to go 'home' after his escape,
These questions don't worry me, in and of themselves.
In short, you are concerned that we get Annael where he is supposed to be at that time.
I'm equally concerned with where he comes from, and who else Tuor is living with. But those depend on whether any other Sinda is allowed to live in Mithrim in Season 4.
Sauron will vanish from the story after being defeated by Lúthien in Season 6, not reappearing for quite some time.
I'm not convinced yet that he has to vanish. In the books, Gothmog and the Balrogs do nothing between Maedhros' capture and the Nirnaeth, and again do nothing between the Nirnaeth and the fall of Gondolin. But we don't send them on vacation, we're giving them more stuff to do in the meantime. We can do that with Sauron, too. He'll be disgraced and demoted after the Tol-in-Gaurhoth fiasco, and will need some time to recover from his "death", but he can still be useful in Angband. If anything, Morgoth will want to keep a close eye on his mightiest (and now disgruntled) servant, rather than let him go set up a secondary realm outside Angband's reach.
Part of the trouble is that if we paint Sauron as only scheming, then yes we'll run out of things for him to do. The best solution is to let him do more than just underhanded sneaky stuff. There are a lot of captives in Angband for him to practice torture, slavemastering, domination, and necromancy over. Necromancy includes inventing how to possess the living and then teaching lesser demons, because that's the ultimate spy game once the Elves get suspicious of escaped captives. There will be an increasing number of Orkish strongholds and slaves to organize and keep in an orderly fashion, especially after the Nirnaeth, and putting things in order is truly Sauron's passion. Whereas Morgoth... may or may not care about the regimental organization and discipline and picky details of Orkish outposts in what used to be Hithlum, Himring, Brethil, Nargothrond, Doriath, etc. While Morgoth just wants to destroy people, Sauron wants to turn Angband into a vast imperial power. And since organized armies are more likely to be successful and loyal than random undisciplined ones, Sauron would be allowed to keep organizing the Orcs and Gaurhoth.