Aaaaaand here I am, already gotten 6 endings in a day...(why can't I stop myself from playing this???)
SPOILERS?
I don't think I have the courage to finish the 2 left, which are the ones which Issac gets abusive and doesn't change or try to be good...but I noticed there's also a "special" ending you mentioned, so may I ask what does this ending tell and do I need to finish all routes to get it?