It's not like they kept it a secret

This makes Ivypool look more foolish than she already is. Even as an apprentince she had bad vibes about the place and yet she still stayed. This whole thing was just badly written in general.

She didn't decide. She was pressured into it. And even if she didn't want to, she didn't have a choice but to stay. She really was dumb about the whole thing. Okay, I can justify the first time her being there because the place was in a meadow or something, but after that, there's no excuse. She went there for attention. She knew the place was bad but she still stayed. The first few moons was by will. She only wanted to leave after she found out the truth, and it was too late to back down then.

That's kinda nonsensical.

She's the equivalent of a child this whole time, even when she finally does realize they were manipulating her. She's never met any of these cats, unlike older ones such as Brambleclaw or Birchfall, etc. Hawkfrost manipulated her, along with other cats, and other DF cats did the very same thing. You're getting on Ivypaw's case making it seem like she should be some all mighty wise cat at her age, when she's not. She's still learning at the time, and she herself realizes her mistakes, but it was already too late.

She thought she was special, she thought she was being trained to be a good cat for her clan, and that Tigerstar and Hawkfrost were actually genuine about their words. These are things they used to lure her in in the first place. She's not like Tawnypelt, she doesn't know what any of them are actually like, especially when they were alive. Take her age into consideration.

It makes sense that she'd want to leave after finding out the truth?? What else would she have wanted to do? She realized they lied to her, do you think she'd want to stay?

Isn't that the scene right before they intimidated her?

Also, I remember it was noted that Tigerstar never revealed when they were going to attack the clans, let alone how. The only thing they said was that they were putting an end to it. For all, we know at the time it could have meant out with the old and in with the new. And keep in mind this is before they get more cats, this is only the third book, halfway through the series, a lot of other cats haven't even join at this point. Imo I don't think 3 books is very early.

All logic goes out the window in regards to the dark forest's indoctrination process. I don't really address this when I rant about ivypool because cognitive dissonance that seems impossible to fathom from the outside looking in is a part of the package in regards to cults. But there is a point where suspension of disbelief starts to end. Tigerstar and Brokenstar were well known tyrants in clan recent history. Yes Hawkfrost did most of the indoctrination process but Tigerstar and Brokenstar wee still active in the training process. Ivypool saw people from other clans in the dark forest, Tigerstar didn't say much about his past life besides he was misjudged. Ivypool defended Tigerstar by saying he was loyal to Thunderclan and that he'd changed in death. But thinking about this for more than 2 seconds causes this to fall apart. Why would someone loyal to Thunderclan train people from other clans? If he was just trying to make people better warriors why would he tell Thunderclan to attack shadowclan? Deep thinking is discouraged in cults but geez what was Ivypool or any of them thinking? This is why I enjoy Breezepelt. He legitimately wanted the clans to burn, particularly Thunderclan, so him being in league with the dark forest makes sense.