Roxas is very quiet when he first appears, but quickly warms up to Axel once he gets to know him and ends up being very cheerful and more open, meeting Xion soon after and the three of them end up becoming an inseparable trio, meeting up on the Station Tower in Twilight Town almost every day to share some Sea-Salt Ice Cream, their favorite treat.
At current he is defeating Heartless to get hearts...he loves sea-salt ice cream in particular, and it seems to have some kind of sentimental value to him, due to his meetings with Axel and Xion and their chats, which meant a lot to him.
In Kingdom Hearts II, Roxas is introduced as a kid living in a digital replica of a city called Twilight Town. Unaware of the virtual nature of the city, Roxas begins to dream about the adventures of Sora, the series' protagonist. He later encounters Axel, a member of Organization XIII who was given orders to either rescue or kill him, and Naminé, a special Nobody fighting against Organization XIII, who tells him he is Sora's other half. Eventually, Ansem the Wise, the creator of the virtual world, leads Roxas to an old mansion where he sees Sora's comrades, Donald Duck and Goofy, sleeping in suspended animation. It is then revealed that Ansem had placed Roxas in the replica of Twilight Town, erased his memory, and implanted false ones to make Roxas unaware of his past and then make him merge with Sora. When he reaches the room where Sora is kept asleep, Roxas rejoins with Sora, allowing Sora to wake up. Sora later learns that Roxas is his Nobody, created during the first game. Xemnas brought Roxas to Organization XIII as he could wield the Keyblade, a weapon which would help them to capture hearts. Roxas later betrayed the organization, and encountered one of Sora's friends, Riku, who captured him to help Sora wake up.
Kingdom Hearts 358/2 Days, a prequel to Kingdom Hearts II, reveals Roxas' life with Organization XIII. Unlike the other Organization members, Roxas lacks memories of his previous life. During Roxas' time in the Organization, he is placed under Axel's watch, and the two eventually become friends. After Axel is sent to Castle Oblivion, Roxas is entrusted with Xion, another Keyblade wielder, whom he befriends before he falls into a month-long coma at the same time Naminé begins to restore Sora's memory. Awakening and attempting to spend time with his friends, Roxas begins to react to Sora's memory restoration as he starts to question why he uses the Keyblade and doubt the Organization's motives. When he discovers that Xion is a replica of Sora created by Xemnas, Roxas feels betrayed by Axel hiding this from him, and is compelled to defect from Organization XIII to find answers and meet Sora. After doing so, he encounters Xion, who tries to attack and absorb him so that she would become the "real" Sora; however, Xion allows Roxas to kill her in battle. The death of his friend, coupled with full knowledge of how deranged Xemnas truly is, makes Roxas decide to defeat Xemnas and release the hearts he and Xion captured for the Organization. On his way, Roxas is confronted by Riku who knocks him unconscious in order to help Ansem and Naminé wake up Sora.
