In regards, Asin's story is still considered a mystery.
Asin's background history and artwork (along with his in-game defeat pose) as well as some of his expressions during specials depict him as a psychopath or lunatic. However, it has been officially stated that Asin does not have a split personality.
Asin's element, water, is also a rival of Jin's element, fire.
Asin is the first character with a temporary GP mission that can only be obtained through events. This didn't happen in the Latin American Server, where Asin's GP mission remains purchasable.
Asin was originally planned to not have a 2nd, 3rd, or 4th job. Disciple's skill progression was equivalent to job changes and he gains a stat bonus every at level 20, 40, 60 and 80 as compensation.
However, with the addition of Mugen, this claim is no longer standing.