Shiki and Sokka are a kind of interesting relationship, especially since they sort of rely on each other to be fairly sensible. They've both been in Luceti for awhile and 'around the block' so to speak. Having briefly been Shiki's 'housemate' in an unorthodox way, he considers himself pretty close to her and he pretty much knows all her secrets now. Between all that and her being his first and only regular 'student', he's pretty protective of her now. She's one of his girls.