9 is one of the members of 1234567890. He is currently a ghost, but was once a normal number. He was killed by 8, undone by Napoleon Bonaparte, only to be killed again by Dora the Explorer, and then coming back as a zombie through the Powers of Weakness.
9 was a member of 1234567890 since his birth. He was raised to use the art of number-fu, like the other numbers. He worked with them for several years, and invented numbers like 99, 999, and even 9999 all by himself. Even the evil 99.9% lie was thought up by him.
Eventually, 9 accidentally fell in a pot of frying oil. He was coated in a delicious breading, and then he fell in a tub full of syrup. Then he fell in more food based item tubs, and then ran at 8 as a prank. 8 leaped into the air, and swallowed 9.
Napoleon Bonaparte walked up, reached down 8's throat, pulled 9 out, and revived him. 9 walked away, but didn't make it for five minutes before Dora the Explorer told him it was his "time". She took his soul to the Devil. The Powers of Weakness took pity on 9, and turned him into a zombie.