This baby dragon is not hostile. You should make him your pet instead! Though he's kind of annoying and catches everything on fire. Don't bother trying to kill him. He's virtually indestructible. He should also be able to keep up with you when you're flying around in creative mode. Great little pal to have around, unless you don't like fire...
Will follow you around and attack most hostile mobs, and will eventually grow up into a large Dragon that you can fly!
How to Kill
Aw. Why would you want to do that? Go away.
Raw beef to tame. Dead Bush to un-tame.
If you tame a baby dragon and he grows up then you have yourself a tamed Dragon! The aging time is random, but when/if he does, you will even be able to ride the dragon!
If you really, really, really, miss your Baby Dragon, try right clicking your grown Dragon with a diamond. Poof. He will un-grow! And yes, a Baby Dragon that was un-grown can grow up again instantly if right-clicked with another diamond.
Found: Red Ant Mining Dimension