Hey, I'm Farrah. Apparently, I'm the daughter of Sam Winchester, so, human, but also part angel. Then guess what? Part demon too! I guess that makes me the most powerful being in the world, which doesn't bother me. But now every demon, plus every angel aside from Castiel, are looking to kill me, and I don't even know how to protect myself. Sure, I've got power galore, but honestly, I have no idea how to control myself. To top it all off, Dean is acting like he hates me. Sam and I are like friends, but I just can't see him as a father. Guess it makes sense, considering...
You are an immortal being, not limited to a species because even the Archangels have no idea what you are. Your only friend is Castiel, when he has time to visit. Even though you are over 6 million years old, you have very little control over your powers, so you stay inside to protect the humans from you. Then Castiel lets you meet the Winchesters, and your new life begins.
I don't own Supernatural or any of the characters though I wish I did.