Roxas

Roxas is Sora's nobody, and the main protagonist of Kingdom Hearts: Tears of Destiny. When Sora is killed, and his soul leaves his body, it becomes Roxas.

Personallity
Roxas, unlike other Nobodies, seems to possess real emotions, stemming from the fact that he, like Naminé, is a special Nobody. Many ranges of feelings come from him depending on his situation. Being Sora's other half, his personality is similar to that of his counterpart, with some differences.

For example, he is far more prone to anger than Sora; temperamental, aggressive, and stands his ground, characteristics that had mixed in his fighting style. He can be arrogant, confident, and determined as proven in his battles, more so when he engages Riku into a fight, proclaiming that he could not beat him no matter how many times he attempted to. His words have bite, and he isn't afraid to speak his mind. He even expressed some dislike for being compared to Sora early on due to their relation, which DiZ notes with amusement in their encounter. This type of main contrast between the boys is sometimes even portrayed in official art, with Roxas almost always having a dark, sort of fierce expression, while Sora's a bit more loose. With a devil-may-care attitude in terms of recklessness, he can be rightfully selfish in certain intervals, but not selfish enough to not, in the end, return back to Sora willingly in understanding. Throughout the game, Roxas is presented as the type to not just let things happen, to twiddle his thumbs and wait when there's something about himself he doesn't comprehend. He constantly rebels against what he's told is his "place" and is a strongly independent individual. On the other hand, Roxas tends to be ironically melancholy and stoic, solemn and distracted, especially as he comes to realize the truth about himself, and in other points when he's confused and lost.

While he is also not as impulsive, like Sora, they both have little patience for people who seem to be bending their will or trying to confuse them. He doesn't have an extreme lust for life as well, not taking everything in with a bright outlook, but he does wish and desire one of his own with fervor. And despite their differences, the traits he and Sora share are shown in how they deeply care for their friends, along with some instances where Roxas is happy, cheerful, kind, at ease, and carefree in good company - even shown laughing.

Roxas also seems to be noted as the smarter half of Sora, as he is not as easily fooled by his enemies and is more likely to think his actions through unless angered. This is slightly changed when it came to Kingdom Hearts 358/2 Days, because unlike his future self that had thorough knowledge of subjects in the fake Twilight Town, Roxas was born with no memories when taken in by the Organization. Hence, he had no information on the simplest topics or objects, making him comparable to a newborn who grows to learn them, and coming off slow and naive due to it. It is why Axel fulfills the role of enlightening him about his questions or thoughts, sometimes making Axel himself tongue tied on how to explain them. Roxas's attitude, nonetheless, was very apparent from the start, telling Axel after he accomplished a mission in the beginning that he could have done that blindfolded, and being easily annoyed when Xigbar calls him "kid" or "tiger".

Another difference with Sora is their heroic status. Often times, Roxas shows how he'd rather not have anything to do with the Keyblade, longing to be a normal kid, with a normal life, and normal friends. This is something represented in Hayner, Pence, and Olette throughout the series, as he is shown a number of times watching them in wonder and interest. On the other hand, Sora, despite that he was much or less the same, and was spurred on by the goal of finding his friends, took on the responsibility more passively without much hassle.

Kingdom Hearts: Tears of Destiny
In Tears of Destiny, when Sora is killed by the Heartless Crystal Behemoth, his body's empty shell became Roxas.