I think that some Nobodies DO have hearts, they just don't realise it. so their memories can be tampered with...
The definition of a Nobody is a being without a heart. Body and soul. Period.
Axel says a funny thing; "You have a heart." But what he's referring to is Sora, it's Roxas's consciousness meeting with Axel's after Axel has died and Roxas has fused with Sora. He also says "Just because you have a next life," meaning that he doesn't think he has one (which might mean his Heartless is still running around and with it alive he has no chance at being restored).
Roxas's memories get tampered with because they're stored in SORA'S heart, to which Namine has access. She doesn't have access to any of the other Organization members' hearts, and so can't meddle with them. I don't think the Organization forgot Sora when all his friends did, either (as far as CoM goes).
There's always her being a Kairi lookalike to tip the scale, too.
Also, no point in leaving the good Memories if they would be without a conclusion. Riku'd forever more not know what happened to Xion; I think that's somewhat crueler than letting him know she died.
If the memories were important enough to him, she'd leave them alone in their entirety. After all, she left the decision up to Sora in CoM; she knew which one was best for him, but she wasn't going to force his hand one way or the other. So if Xion's death bothered Riku so much that Namine needed to erase them, they'd be memories he wouldn't want to lose. It's a paradox.
But again, considering KH's largely platonic relationships and the fact that Riku and Xion don't know each other for very long (and don't exactly fall head over heels for each other, if the scans thus far are any indication), I don't think she'd affect him to the point that he needed those memories erased.
If Xion really is related to Sora's Memories, Namine'd hesitate but go along with it.
Also, again with the kindred spirits; Namine'd disappear if she could and all but wiped herself out from the Heart of the person who cared about her the most; seeing Xion in a similar situation would get her to do it.
Good point. I was thinking she'd protest every step of the way, but if she has that understanding already she might just snap into witch mode and go through with it.
Well, Axel and Roxas had more than enough reason not to mention her even if they remembered, I agree (especially since Roxas didn't remember anything during KH2) but that still leaves us with why didn't Riku respond more than he did (aside from KH2 being badly written) especially with not only Namine but Kairi running around with him as well, and then DiZ and his reports as is mentioned repeatedly (unless, of course, for one reason or another, DiZ never cared specifically for Xion and just labeled her as another member of the Org, leaving her importance to be dictated by Riku and Namine).
I'm trying to think of a time when the subject could have come up. I'm not disagreeing and he absolutely should have said something somewhere, it just seems like he didn't really have a chance to go "Oh by the way, there was this chick Xion, she was awesome and stuff, but she's dead now, so."
Sweetheart >:3
Her making Sora choose to remember her or not; her all but running away from their promise to be friends again by not only dumping their reunion on her meeting with Roxas, but going along to disappear into Kairi afterwards (and her being Kairi now holds no water to me; Sora knew Kairi as Kairi at the end of CoM and still promised Namine as Namine that they'd be friends, so to me, she broke that promise).
She has it going in spades, actually.
Aw c'mon! Cut the girl some slack! I actually appreciated her making Sora choose, because she was very frank about it--this is real, this is not, but I've manipulated you enough and I'm not going to decide the rest of your life for you too--plus it was Namine or his older memories, no two ways about it. She had his trust then, but she hadn't earned it, so I can't see her just saying "Yeah I broke you, but I'm gonna make you better now like it or not, sweet dreams."
Their reunion wasn't really under her control. Sure, she could've run into him earlier to say hi, but she was busy running around fixing him, escaping DiZ, sending Axel after Kairi, grabbing Kairi out of the castle dungeon when she managed to get her ass kidnapped twice in a row, etc. As much as Sora meant to her, he wasn't the priority (meeting-wise, anyway).
She apparently wanted to go back to Kairi, I don't know why, maybe she just hated herself that much; but it's also possible that she didn't have a choice for one reason or another. It's still really unclear what PART of Kairi she was, and if her absence was going to be physically harmful to Kairi or herself down the line. Plus, she most likely didn't know who she was and what was going to happen to her at the time of the promise. She definitely had plans to meet up with him when he woke up, but DiZ threw a wrench in that when he decided to kill her off and Riku plucked her out of harm's way. That part was unavoidable.