can we all agree that whilst yes, Dean tried his best with what he had and what he knew to help Sam detox, there could've been a better way than to stick him in the panic room and lock him in there? The whole thing boiled down to miscommunication and lack of trust on both parts

Dean's mind was obviously clouded with his own prejudices against Sam's powers and jealousy over Ruby and Sam was hell-bent on killing Lilith for revenge AND being manipulated by Ruby who latched onto him at his most vulnerable. There were outside factors damaging them both

They were both manipulated by angels and demons, subtly making them turn on each other. Dean didn't make the best choices and neither did Sam but honestly, and not to justify their actions but after analyzing I consider them both more of victims in the whole situation

Heaven against Hell that's what it was at its core and the main antagonists here I think were the demons and angels. They were each doing their part. Ruby & Cas played a huge part in convincing Sam & Dean respectively they were the 'chosen one'.