Oh boy, where to begin. Let's start with it's poor set-up, that is to say, there basically is none.
While Aqua and Ansem the Wise continue to wait exactly where we left them in Blank Points, Ansem SoD shows up out of nowhere and demands his former teacher to reveal information regarding a particular test subject, a girl, whom he had lost track of long ago. When Ansem the Wise either plays dumb or genuinely explains he doesn't remember, his former apprentice attempts to violently force the information out of him by.... returning him to the Old Mansion? Ummm, ok.
Disregarding how he even managed to track them down in the first place within the vast and confusing realm that is the RoD (cause unlike Mickey in this game, he had no means of finding either of them for as far as we're supposed to believe), where is this even coming from? Why is this girl so relevant to Ansem SoD's own specific goals? It's clearly urgent and important enough for him to kidnap Ansem the Wise out of the blue, but why? Well unfortunately we're never told. Outside of "her" (the girl) being close friends with Isa and Lea, this plot point regarding Ansem SoD's motives is never brought up again. So why then include this scene, which intrudes on the story of other characters (whom are actually relevant to this finale) if there's no actual pay off or justification? Anyway, moving on.
Aqua interferes when Ansem SoD closes in on her new companion and tells him to leave. This prompts the heartless to attack her without warning. For some reason, Aqua doesn't have her keyblade, and when Ansem SoD outwardly ask her about this, she simply says "don't need it" and proceeds to attack the Guardian bare-handed. Despite her nimble acrobatics and surprisingly good hand-to-hand fighting ability, she is quickly overwhelmed and subdued. This results in Ansem the Wise pleading for his apprentice to let her go and he'll go with him. After this, Aqua makes one last attempt to interfere, but doesn't even phase the guy (who just casually blocks with his arm). Feeling some kind of sick pity on the Keyblade Master, he has the Guardian shoot out a ball of darkness (that she doesn't even bother dodging) which infests her heart (corrupting her), and throws her into the "abyss." (or so Mickey later called it).
Soooo, everything's wrong with this. WHY exactly doesn't Aqua have her keyblade? We know it ends up on Destiny Islands, but try as I might, I can't find a single explanation for how it got there. Not from Aqua. And not from the game. Sora just delivers it back to her later on and they never once discuss it. From a plot perspective, the only reason I can see for the writers doing this was to make it so that Aqua didn't have any effective means to interfere with Ansem SoD, likely because they couldn't think of a better, more justifiable reason to have this Keyblade Master lose to someone Sora was able to defeat in KH1, and Riku was able to beat in CoM (without a keyblade). Still, as absurd as that reason is, none of that explains why Aqua, at the very least, didn't use some form of magic (which was her strong suit any way) against the heartless (Ansem I mean) when he attacked. It's cringey and somewhat insulting that they expected me to be invested in this revelation and not ask these basic questions. Then there's the whole corruption process itself. It just.... happens. No warning, no explanation, and no precedent (certainly not to that scale). I don't even get why Ansem SoD did that in the first place, but I know now why the writers chose to pull that stunt. Mickey and Riku go in and out of the RoD in the very beginning of the game, and they end up at the exact spot on the Dark Margin where Aqua and Ansem the Wise were last at. But they immediately go back empty handed cause they simply don't find anybody, and because Aqua's apparently deeper in the darkness then they thought. So basically the decision was entirely made so that Aqua's specific predicament (not even AtW's, just Aqua's) would be prolonged until much further in the game. More specifically so that Sora, who didn't even remember her- unlike Riku and Mickey(as revealed later), would be the one to rescue her. That's.... really bad.
And then there's the fact that this pretty much spits in the face of Aqua's promise to protect whomever found there way to her in the RoD. This was her one and ONLY chance to fulfill that promise, and it's completely compromised by a character who shouldn't even be a threat to her, and a plot point regarding a nameless girl that has zero relevance to the actual events of this finale. Like, wow. Oh, but I found out it only gets worse.
Once Riku and Mickey actually find Aqua (now anti-fied) she starts going on about how Mickey is "too late", and that he "abandoned her for over a decade." "Knowing what it would do" to her. Apparently she "waited forever." Uuuuuh, what? And then Mickey actually responds to this by APOLOGIZING, and saying it's all HIS fault. Aqua then goes on about how lonely she was, and "how frightening it is to have no one." Keep in mind this was immediately after she mentions stopping at the Dark Margin. She then proceeds to attack Riku, who struggles to fend her off, and Sora quickly comes in to save the day. Working together, he and Riku free Mickey, and then he saves Riku from another attack coming from the deranged Keyblade Master. After single-handedly besting her in combat, she is immediately returned to normal upon her defeat, and Sora, Riku, and Mickey bring her back to the RoL (which prompts a strong emotional response from her).
.....Oh, GOD this was bad. When I first saw this scene I genuinely had to do a triple take, and every single time I felt more and more sick. So not only was the dialogue in this scene simply inaccurate in every way and must have been talking about a story I've never scene, but it was also a huge waste of time, and ended up just being the Sora-show again for literally no reason (as I hinted earlier in the post). First of all, literally everything Aqua says is just flat out false, and anyone with a brain could easily tell she was just spouting edgy nonsense. SHE threw herself into the RoD in BBS, and NO ONE knew where she was. Mickey says this in 0.2 multiple times. Aqua says this herself multiple times. Then, in the end of 0.2, she threw herself BACK into the RoD of her own free will and proceeded to wait for what I KNOW wasn't another decade. Never mind the fact that she was literally sitting and waiting WITH Ansem the Wise on the beach the very last time we saw her (which based on another Twilight Town cutscene was not very long ago at all), and we learn that never changed till Ansem SoD showed up. Where is all this "you abandoned me for over a decade" and "do you know what it's like to have no one" talk coming from? Not a single word of dialogue from her in this scene makes any sense, and Mickey and Riku just agree with her and go along with it. Anti-Aqua even goes so far as to imply Mickey should have known she lost her keyblade (and somehow THAT was what left her stranded). Like... what? Then this all just gets resolved and we get no follow up from ANYONE about the fact that she literally tried to kill them/cast them into darkness (again, for reasons that are simply false). Then when they later apologize about not coming sooner (this was after they regrouped in the Mysterious Tower), Aqua flat out states that they never let her down. Oh my gosh the writing made me want to cry in sadness and disbelief after I saw everything regarding this. Then every subsequent time Aqua tries to "protect" anyone, or step up and fight, she just utterly fails, or does NOTHING every single time. And every single time she needed to be saved by someone. Isn't she a Keyblade Master? WHY is she losing track of her keyblade- litterally the only thing she has to keep track of (jeopardizing herself, her promises, and the well-being of Ventus) and making a mockery out of herself? WHY is she spouting actual nonsense about a fallacy that must have come from some intense delusion? Just... I don't understand what the logic was supposed to be, and I can't see this as anything more than an insult and a waste of time. In no KH game before this have I actually felt like the writers were testing my basic intelligence, but I guess reality just isn't very forgiving.
All in all, they completely butchered her character arc in my opinion, and it's a darn shame most fans likely won't care about this. Sorry if I sounded a bit aggressive when explaining this, but the whole thing genuinely got me pretty heated. Thanks for being patient with me.