There were NO tattoos mentioned in the first book if I recall right, and a couple were added (paw print and.. I want to say there's another one). There's a FAQ somewhere where basically the cover art and the tattoos are explained as they represent what's inside the book, not that Mercy has other tattoos other than the couple she has, just that it's sort of the artist taking liberties. So more vampires, more tattoos related to that etc. It annoys me that it's not true to the book and Mercy is way more busty/sexed up on the covers than she is in the story, but at the same time - it IS lovely artwork and it's all marketing I guess. I feel that the author likely has little to no say, which is usually the case with cover art.