Well sometime, for non malevolent users/watchers, a big watermark right in the middle of the pic or on a detail can be annoyingh (especially when using as a wallpaper for everyday or such) aside from a discret copyright notice, a signature in one corner, two things can protect you a bit from dirty thieves and pics leechers... 1) make a distinctive feature visible on your character, it can be a scar, a tatoo, or something 2) have a very special drawing/postworking style that is easily recognizable, not only to you but to people who like your work for what it is. Chances are that if THEY recognize your style on a website it isn't supposed to be on, or fromsomeone who claims its his, they will help and report it