In Birth By Sleep, Maleficent transforms into her dragon form by her own will to fight Aqua.
In Kingdom Hearts 1, however, Maleficent didn't transform into the dragon on her own. Instead, Riku (possessed by Xehanort's Heartless) had to release her heart and fill it with darkness by using the Keyblade of People's hearts. She said "finally... this power!". She uses the word "finally", yet she already has shown the ability to use that power.
Why was Maleficent able to do it at will in Birth By Sleep but not in Kingdom Hearts?
In Kingdom Hearts 1, however, Maleficent didn't transform into the dragon on her own. Instead, Riku (possessed by Xehanort's Heartless) had to release her heart and fill it with darkness by using the Keyblade of People's hearts. She said "finally... this power!". She uses the word "finally", yet she already has shown the ability to use that power.
Why was Maleficent able to do it at will in Birth By Sleep but not in Kingdom Hearts?