So, without further ado, onwards to...
Axel x Roxas x Demyx. I believe this is a very difficult pairing to mesh for two reasons: 1, they are nobodies and nobodies can only fake emotions, and 2, we see very little interaction with Demyx asides from his fight with Sora. However, this has not stopped fans from writing for this pairing, and in fact it has a pretty decent popularity out there. So the questions we might ask is "why use this pairing" and "how does it work?"
The link between Roxas and Axel is definitely there. Axel admits that he would miss Roxas if he left the Organization and he also says that around Roxas, he felt as if he had a heart. Namine also mentionis that Axel and Roxas were "best friends," although its up in the air as to what being a best friend means to a nobody. Their early relationship - namely, when they were in the Organization together - seems to be one-sided. After all, Roxas left the Organization without a second thought for Axel, even claimed that Axel really doesn't care no matter what he says because the bottom line is, they don't have hearts.
However, this is where it gets complicated. When Roxas gets puts into Twilight Town, he is given a new personality, and this personality seems to care a lot more about things then Organization!Roxas. I compare this personality addition to what happened to Replica Riku, they are given fake hearts. Even though Roxas eventually comes to realize that the memories that make up his heart were never real, he defiantly tells Diz that "My heart is my own!" Perhaps he accepts that it was never real and doesn't care, or simply didn't quite believe it yet. However, with this new personality, he sees Axel in a new light, and even seems remorseful when he finally remembers his old friend during their last battle together.
The biggest outcome of this new personality, however, is after the scene in Betwixt and Between, when Axel sacrifices himself for Sora. That is when Roxas steps out of Sora's darkness and fights him for the sole purpose of finding out "why did he choose you?" I interpreted this as meaning, why did Axel choose Sora. Why did Axel sacrifice himself for Sora, but was willing to kill Roxas for the Organization?
Axel said that he felt as if he had a heart around them both, but could it be that the only reason he felt that was because Roxas was Sora's nobody? He is linked to a very powerful heart, and if he can feel Sora, it's possible that it can bleed over to other nobodies that are close to him. Therefore, Axel would feel something near Roxas, as well as Sora.
So the question is, was it just Axel that felt it, or would other nobodies feel it too? Like say.... Demyx. We get one reference to the relationship between Roxas and Demyx, and that is in the scene where he pleads to Sora, "Roxas, come back to us!" However, we must remember that he was under orders to "liberate Sora's true disposition," and that likely meant to tap into Sora's anger (whose ultimate source is Roxas) so that he would destroy lots of heartless.
Demyx has chosen a facade for himself in which he is fearful of fighting, but that doesn't meant that the thought that Roxas was someday going to destroy him didn't cross his mind every now and then. It may have been easy for Roxas to dominate Demyx if he felt like it if he threatened him with his keyblades. Since Axel is Roxas's "best friend," he probably had some bullying power himself, since hurting Axel might have meant incurring Roxas's revenge. Although every nobody can not feel, every nobody wants to exist, and anything that threatens their existence really bothers them.
That leads us to the million dollar question. In the Organization era, how do three nobodies without hearts form a triangle? I propose the following scenarios:
a) Organization members that are near Roxas feel as if they have a heart because of his link to Sora. Therefore, there might be a bit of fighting over Roxas or trying to be his friend just to have those feelings - or the opposite, wariness.
b) Control of the keyblades. Roxas is a tool in the Organization, therefore whoever controls Roxas has greater power. We saw the nobodies attempt to do this in Chain of Memories with Sora and Riku. Although Roxas can't feel, he can still remember the things he does in his day, so whatever nobodies fills his head with the best memories gets to be his "friend." I think that although Demyx acts scared, he may actually be shrewd enough to try to enter a power struggle versus Axel to gain Roxas for himself.
c) Nobodies can act on feelings they strongly remember from their old hearts. For example, Xemnas only remembers a heart's anger and rage. Axel probably remembers energy and jealousy. Demyx probably remembers fear. Roxas probably remembers belonging, because Sora always longs to be with his friends. So they may have some semblence of emotion that they can act on, even if its not a "full" emotion per se.
Then, of course, Roxas after he gains his new personality is a lot easier to form a relationship with. I have seen a couple of AUs and canon fics that have capitalized on this. But in any case, those are my thoughts on the Axel x Roxas x Demyx pairing. How have you made this pairing work? Do you believe that this pairing is possible at all? This discussion is now open!