Now I'm fairly new to the Supernatural franchise (I just started season 3) but I ended up either accidentally reading too much wikia's or my friends have told me about things so I know a fair bit into the future of the show.
I was wondering, since there are obviously angels who have turned "evil" by way of killing other angels or just in generally doing evil things, can a demon in the show be "good"? Ruby kinda helped Sam (from what I've seen so far) but she just wanted Lucifer out.