THE KEYBLADE WIELDER, SORAThe following information is the way Saix interacts with Sora in the video game version of Kingdom Hearts II. Different games give off different information with this relationship. To view Saix's relationship with Sora in other games, try each individual section in the main navigation above.
Saix plays a big role in the whereabouts of Kairi through out Kingdom Hearts II. Seeing as how she means the most to Sora, he intrigues Sora into cooperating to get the Organization's end goal, Sora using his keyblade to fight heartless in the series and release their hearts. Telling Sora he is protecting him from the Organization member Axel, he blames Axel for the distress Sora is getting. He tells Sora that Axel's main goal is to turn him into a heartless and take everything away from him. Saix continuously manipulates Sora, telling him not to end up like Riku, which clearly makes Sora's mind want answers to Saix. Though Saix is only messing with Sora for Xemnas' main goal, he obeys and tries to mess with Sora's mind and heart in order to get what he really wants: Kingdom Hearts.
Saix runs into Axel and Sora talking, and although he is unable to catch Axel, he stays awhile and talks to Sora. Sora was previously just being told by Axel not to trust Saix and that Saix will be using him for an ultimate goal, nothing sincere. Saix tells Sora that he is taking good care of Kairi, which irritates Sora. He wants her back, and Saix tells him to prove to him how much Kairi means to him. Sora gets down on his knees and begs for her back, laughing, Saix doesn't understand why someone would belittle themselves for someone else. He asks Sora to take his anger out on the Heartless instead of himself. After Saix disappears, he realizes that Sora is smarter than the Organization had hoped for. He tells Xemnas that Sora is realizing the more Heartless he kills, the more he's falling into a trap.
In the end, Kingdom Hearts is quickly filling up and almost complete. However, Sora comes in to end the fun for Saix. Saix refers to him as "Roxas," which pisses off Sora because he doesn't want to be referred to someone he isn't. Saix laughs at him and says "different name, same fate!" as he starts to attack Sora for battle. Sora defeats Saix, but before he disappears, Saix reaches out and asks where his heart was? Sora pays not attention to the death of Saix like he does for other characters like Axel, who actual like him and protect him. Saix dies before Kingdom Hearts is able to be completed from Sora.