From an interview that can be found here (it's vaguely spoilery, so feel free to avoid it if you don't want to know anything):
Your character, Castiel, is accused by Anna [Julie McNiven] of not being able to feel real emotion, but he seems to have a real affection for Dean [Jensen Ackles]. How do you work with that sort of dichotomy?
Collins: Yes, how do you explain the homoerotic tension [laughs]?
Oh, Misha... *sigh* Can it be November now?!?!
Your character, Castiel, is accused by Anna [Julie McNiven] of not being able to feel real emotion, but he seems to have a real affection for Dean [Jensen Ackles]. How do you work with that sort of dichotomy?
Collins: Yes, how do you explain the homoerotic tension [laughs]?
Oh, Misha... *sigh* Can it be November now?!?!