Sora

Sora is a character in the Ansem Retort series of webcomics.

His personality involves serious long term and short term amnesia and crippling stupidity.

Backstory
Nothing is known about Sora's backstory other than the cause of his amnesia (being Namine knocking him over and giving him a concussion), and his association with Cloud (even though you don't know what kind of relationship they share)