Axel would be Deva of Flames, and he'd talk in bright red. Personality-wise ... he could go two ways, and it's entirely dependent on whether or not Roxas is still around in this future.
With Roxas around: Eventually gets his heart back. No longer a traitor, he's ridiculously loyal to his friends, of which he goes around trying to make many. Less of an asshole: that attitude has shifted into joking and teasing. Loves a challenge, and goes around trying to fix really difficult problems with worlds as a result. (Yes, going around and helping people. Happily.) Still says that he, Roxas, and Xion (provided she's there) are "inseparable". When he's not spending his free time with them, he spends it with Saïx, who he tries to work alongside as much as possible (again, provided he's around). OR MAYBE ALL FOUR OF THEM HANG OUT TOGETHER idk.
Without Roxas around: Even more of a manipulative asshole than he is now. Tends to create worlds that are either doomed to end in fire and war, or are full of sickeningly happy people determined to follow their dreams. (The residents of the happy worlds have an odd tendency to have bright blue eyes and either blond or black hair, with the occasional brunette.) Will be someone's best friend right up until he stabs them in the back and leaves everything they worked for in ruins (or just takes it for himself). Probably widely rumored to have more than a few screws loose. Thrives -- insomuch as he can -- on conflict.
AXEL
With Roxas around: Eventually gets his heart back. No longer a traitor, he's ridiculously loyal to his friends, of which he goes around trying to make many. Less of an asshole: that attitude has shifted into joking and teasing. Loves a challenge, and goes around trying to fix really difficult problems with worlds as a result. (Yes, going around and helping people. Happily.) Still says that he, Roxas, and Xion (provided she's there) are "inseparable". When he's not spending his free time with them, he spends it with Saïx, who he tries to work alongside as much as possible (again, provided he's around). OR MAYBE ALL FOUR OF THEM HANG OUT TOGETHER idk.
Without Roxas around: Even more of a manipulative asshole than he is now. Tends to create worlds that are either doomed to end in fire and war, or are full of sickeningly happy people determined to follow their dreams. (The residents of the happy worlds have an odd tendency to have bright blue eyes and either blond or black hair, with the occasional brunette.) Will be someone's best friend right up until he stabs them in the back and leaves everything they worked for in ruins (or just takes it for himself). Probably widely rumored to have more than a few screws loose. Thrives -- insomuch as he can -- on conflict.
/clearly putting too much thought into this