Who is Axel in Kingdom Hearts?

Answer 1

Axel, the Nobody of Lea, is No. 8 of Organization XIII, and the best friend of Roxas and Xion. He wields chakrams of fire. He grew up as 'Lea' in the hometown of Radiant Garden, with his best friend Isa, who later becomes "Saïx" (another future member of Organization XIII).

Although it appears otherwise, Axel and Saïx don't hate each other; they just don't get along as much as their human forms did. Other human forms of Organization XIII appear in Kingdom Hearts: Birth by Sleep.