I don't remember when I first started doing this. I feel like it was back awhile ago and I never thought anything of it really. I just thought of it as me being "bored" and just entertaining myself. But after awhile it felt like a really good sensation to do it. Like I got some sort of relief out of it. My lips have never bled, but my upper lip, the only one I bite or pick is the only one that suffers..and it gets irritated and sore after awhile..sometimes it gets swollen and larger. It stings too but I like the stinging sensation a lot. I don't know if that is weird or not..Like I'll hold my finger up to it and it starts stinging..and I count til 3 and then let it off. Hm I never imitated this behavior I just picked it up for some odd reason. I don't think this is a normal thing to do..apparently it isn't but I'm glad I can finally relate to someone about this. My girlfriend kept giving me looks whenever I'd bite more haha. I do it more when I'm stressed..but I do find myself doing it occasionally when I'm not stressed..and I just get that urge to do it.