User blog comment:ChishioKunrin/Why do people mix up Summer and Yang's mom?/@comment-25405817-20150527040938/@comment-25555436-20150527180029

It was different in KH, Zolnir. You don't need to let darkness enter your soul, you only need to lose your heart. Of course, that being Square, there are always exceptions (Riku). And that being Disney, if you become a Heartless you can easily go back to normal and recover your heart (kinda) in just a couple of minutes through the power of Deus Ex Machina.