Apparently, people have been getting tattoos for over 5000 years, but they've only recently gained popularity in Western culture (source). To say they've gained popularity is a bit of an understatement. There's a tattoo explosion going on around us. Yet, having tattoos are still controversial in Western and other societies.
In our discussion of symbols in The Girl With The Dragon Tattoo we suggest that Salander's tattoos are a map of her past, and we hope to learn more about them in the future. In The Girl Who Played With Fire Salander has the wasp tattoo on her neck removed. Wasp is her hacker name and she fears the tattoo is too conspicuous. In this, the final novel of the trilogy, tattoos seem to symbolize several things, even though we never learn the meaning of Salander's rose tattoo or her tattoo of a Chinese symbol.
Salander won't discuss her tattoos with Dr. Jonasson, but she does she show him her dragon tattoo. He says, "It's beautiful, but it must have hurt like hell" (9.125). She replies, "Yes, […] it hurt" (9.126). Salander's tattoos are not like books that the public is free to analyze. Yet, she does allow select people to appreciate the beauty of them, beauty that can be seen as something born of great pain and suffering. Salander's ability to transform her suffering into something beautiful is revealed in pondering her tattoos.
After Nils Bjurman rapes Salander in Tattoo, she tattoos "I AM A SADISTIC PIG, A PERVERT, AND A RAPIST" (14.93) on his belly. This is not just vengeance but her version of justice. She tattoos him to deter him from showing himself to women he might abuse. When he dies, the tattoo is a clue that he probably raped somebody. Eventually everybody learns that that somebody is Salander.
At her trial, Teleborian testifies that Salander's tattoos "are no normal measure of fetishism or body decoration" (26.80) but rather "a manifestation of self hate" (26.71). Salander's lawyer announces that she herself has a tattoo and asks Teleborian "At what percentage of tattooed body surface does it stop being fetishism and become mental illness?" (26.83). He's at a total loss for words. Plus, he's trying to say that Salander's tattoos are evidence that she is dangerous to herself, and justify his keeping her in restraints for hundreds of days when she was a teen. As Salander's lawyer points out, she got the tattoos long after she was at St. Stefan's. All in all, Salander's tattoos help her win in court and help her get the declaration of incompetence revoked. Salander is free to have tattoos and to live as a citizen in her native land.