OK so there has been alot of theories going on about who Betty is. Some people think that its Doctor Princess because she has a red gem on her forehead which looks like the red gems on the ice crown, and that she has the same glasses and lab coat like Betty. Others said that it is Princess Bubblegum because she has same glasses and lab coat like Betty, and she has the same hair as Betty (Well almost.). One note to say that both Doctor Princess and Princess Bubblegum have a purple bug in the pocket of their lab coat like Simon Petricov's gray coat. But, at the ending of the new episode Betty, (SPOILER ALERT!!) Betty fly's of in the magic carpet (Which was Ash's magic carpet.). So is Betty Doctor Princess or Princess Bubblegum?? You decide.