First off, bad news everyone, take a deep breath, sit down, grab a tissue or your pillow or puppy, kitten, bunny, frog, lizard…whatever it is that helps you get through bad news. Okay. Is everyone set? Good. I’m sorry to have to be the one to tell you this but Hellatus is halfway done. That’s right. I’m sorry to say that we have reached the mid-point of 2010 Hellatus and there’s nowhere to go but quickly into the new season. 
Everyone all right? Okay. Remember, together we can manage the fact that soon Hellatus will be all over and there will be nothing to do but enjoy a new episode of Supernatural each and every week…darn. Jas’ couch is always open so pile on if you need to.
Now, with the bad news out of the way it’s time to give a little love to Castiel. Castiel stormed onto the scene at the beginning of Season 4 and I for one can’t imagine my Supernatural without him. Like Bobby Singer, Castiel quickly stole my heart. 
Enter one bada** angel with a mission for Dean from God. One of the coolest entrances ever.
Castiel is curious about humans as evidenced by his flipping through the spell books Bobby had on the table as well as his incredulous realization that Dean doesn’t think he’s worth saving. That doesn’t stop him from quickly getting down to business and he doesn’t brook any of Dean’s insolence at the end of Are You There, God, It’s Me, Dean Winchester:
“You should show me some respect. I dragged you out of hell, I can throw you back in.”
It doesn’t take long for Castiel to start to find some sympathy for Dean and what he’s facing though. Castiel’s purpose in sending Dean back in time in In The Beginning was to speed up the learning curve and get Dean on board with how long Azazel has been putting his plan into works, however, Castiel learns a little something along the way; he cares.
 Castiel’s next appearance has him meeting Sam for the first time; still unaccustomed to human interaction it’s a very uncomfortable meeting for both:
While Dean continues to generate sympathy in Castiel for all that he’s facing, Castiel is still focussed on his mission and being resolutely loyal to heaven, thus his appearance with his new angel-sidekick Uriel is decidedly not filled with forgiveness nor sympathy for the choices some have made: 
“Anna has to die.”
And yet, at the end of Heaven and Hell, Castiel’s sympathies arise again, this time for Anna.
There is a four-episode break in Castiel appearances and when he returns at the end of Death Takes a Holiday and captures Alastair there is something very Cheshire Cat about his appearance, Cas is clearly pleased with his cleverness.