Name: Castiel
Source Canon: Supernatural
Age: As old as creation, or perhaps slightly younger; physically in a vessel that's in his mid-30s.
Role In Canon: OU
Canon-point:
pre-4.20 The Rapture, possibly April 30th, 2009 (the day it aired)
History:
Castiel's background can be found
here on wiki as well as
here on Super-wiki.
Personality:
Castiel is, first and foremost, a soldier of Heaven. His true form is approximately the size of the Chrysler Building, and even a slight peek at his true form will cause the human's eyes to burn out. His true voice is piercing to the unaided ear, and he requires a vessel to communicate with humans, thus his human vessel Jimmy Novak. He is not an angel that most humans think of, quoting Dean, 'I thought angels were supposed to be guardians. Fluffy wings, halos. You know. Michael Landon. Not dicks.'.
As a soldier of the Lord, he is created solely for the purpose of following God's will to the word. He never questions, never doubts. When God commanded the angels to rescue the Righteous Man, there was no hesitation, just a single minded determination to raise Dean Winchester from perdition. Like other angels, he has no human emotions, as they are 'the doorway to doubt'. All he has is his unshakable faith in his Father, and as the series progresses, his faith in Dean and eventually humanity as a whole. Castiel sees the human race as his Father's works of art, and admires them for their free will and passion for everything though he doesn't understand free will until later on when Dean induces him to question himself and his orders from Heaven.
Castiel doesn't mince or sugarcoat his words. If he wants to say it, he will say it even if it emotionally hurts the human he's talking to. It may seem tactless, but remember that Castiel doesn't have human emotions, so he does not know what is right or wrong in the human sense. In the millennia he's been alive since creation, he's only been watching the human population but not once interacting - the Tower of Babel, David and Goliath, Sodom and Gomorrah - so, in the fall of 2008, (during the rise of the Righteous Man from Hell) that was his first real first-hand experience with humans. To a very large extent, Castiel doesn't understand references. You can toss cultural references, music references, even little analogies and similes - he wouldn't understand it, and he'll give the person a little head tilt and confused look in return.
If anything though, Castiel is persistent when he sets his mind and will on something. He was the first to reach Dean and bring him back from Hell, he doesn't stop reminding the hunter that good things will come when he believes in it, and he won't stop fighting even if he's down, powerless and bleeding. As a warrior, he won't quit while he's ahead, and this applies to everything he's doing, be it fighting demons, his angel brethren, or even picking up human mannerisms and emotions, slow as he's learning them. He's blunt, honest and straightforward to a fault; he doesn't understand the need to lie or reassure people, and that brings back to his lack of and of human emotions.
As Jimmy Novak, his vessel, puts it, 'I mean, angel inside of you, it's kinda like being chained to a comet', Castiel is never patient. He's constantly moving forward, pressing on, and he won't stop for questions or useless small talk - even if the other party is persistent, he will only give short, clipped answers, or not answer at all and change the topic altogether. He's a tactician, employing ways to get to where or what he wants no matter the consequences. Castiel is also as loyal as he is resolute, his first allegiance being his Father, and then later on being Dean, his faith in the human unshakeable as the one he has in his Father.
Abilities:
Being an Angel of the Lord, he has angelic abilities. He is a fighter, capable of wielding an Angel Sword, a special sword that only angels possess and able to kill other angels with a deep stab. Even though his vessel is a slight man of about 5'11, he is able to manifest his strength through his vessel, enough to toss a full grown, 6'1" 180+lb man about like a ragdoll, especially when he's angry. He is telekinetic, moving things easily without touching them, and he's well-versed in languages and lore.
He can fly as well, but it's too fast for the human eye to perceive, and thus it seems that he is teleporting. Indications of him flying in and out is the distinct sound of wingbeats, and his sudden appearance and disappearance. He can travel through time; also, he can kill lesser creatures with a concentrated touch, usually to the face or the forehead, and release a blast of light to kill all monsters/demons in the room in one fell swoop.