So for Demyx day, I shall list five Demyx "headspace" facts. All this means is that I will be writing five of my own "self-fanon" facts about him.
1. Before losing his Heart, he was a high paid teen model, and of course, a talented musician. He bought his first car(a Porsche-type) when he was sixteen. At that time, he was making six figured sums. Needless to say, he was happy. He pretty much had it all, and grew up loved, cared for, and well disciplined despite being spoiled. Sixteen was his best and worst year as he lost his heart a few months after getting his car.
2. No, he isn't stupid. Far from it. However, he does suffer from disabilities due to brain damage while he was still a fetus.
3. Demyx perfectly despised Axel at first. In fact, he wasn't comfortable with any of them, except for Xigbar, and even then, not too much. His first impression of Axel was that "he looked like he wanted to eat me, and really believed that he could." He tried to avoid Axel for a month, but failed when he ended up making enemies. Axel, long in a similar situation and always wanting to "score" with Demyx, took advantage of that.
4. In all the Organization, Demyx is fairly close to Xigbar and Luxord, was a friend of Marluxia's(also a cause of tension between Axel and Demyx), and is ultimately closet to Axel and Roxas. Course, in the case of Axel, he doesn't always want to be. He is distant, but respectful to Xemnas and Xaldin. He detests "The Four Horseman of the Asscopolypse"(Vexen, Lexaeus, Zexion, and Saix) and avoids Larxene as though she is AIDS in human form.
5. Demyx is the only person in the Organization capable of genuine kindness, and he is the only one who believes that they still have Hearts. Everyone, especially Axel, knows that Demyx knows better. Roxas claims that Demyx just "doesn't want to be mean like the rest of them". Demyx is far from an angel, but is also by far the most humane member of Organization 13, and that fact has pissed off many members, especially Axel and Saix.