YES, DAMMIT, Cas!
Many fans won’t let any blame come to Cas….ever….but if you look at his actions throughout the series he has MANY moments where he is not only NOT loyal to the Winchesters but actually ACTIVELY screwing them over. Some of his actions cause some of the most hurtful and dangerous situations to the Winchesters. He is often so misguided and instead of leaning on the Winchesters for advise or help he has a definite streak of hubris that is neither helpful nor becoming. HA! Another flawed dick angel.