Develon is an evil bubble dragon that made his first appearance in Puzzle Bobble 4, and has been a reoccurring character ever since. Unlike our hero brothers Bub and Bob, Develon has wings allowing him to fly and he also has a few other special powers. These are, but no limited too, being able to transform into a bat and materialize as a demonic shadow before taking physical form. He also shows himself to be able to set himself ablaze in blue flame, and fire lasers from his mouth at his foes during battle.
Develon is very much a selfish villain, usually only serving himself and his own goals. However, there have been a few exceptions in which he assisted Dreg. This has only ever been short-term though and he has since assisted Bub and various other characters. It really shows that Develon is only out for himself and his own evil ends.
A lot of this time seems to be spent sabotaging Bub and Bobs quests, and to some, he is believed to be a demon.