Tomie is a metaphor for domestic abuse.
Tomie is driven by venagence towards other humans.
Tomie used to be human until her first death.Notably, the first story doesn't feature much of the hallmarks of the series. For instance, Tomie appears to actually care about Reiko and appears upset when she runs away, while usually she treats women with contempt. In addition, it is implied in that story that Tomie and Reiko were childhood friends, meaning Tomie grew up. Finally, this story treats Tomie much more sympathetically than the rest of the series, showing that while she was not a great person, she was pretty lonely and only two people really cared when she died. Either this is Early Installment Weirdness or perhaps it was the origin story for the titular monster.
- Additionally, the signature under-eye circles don't appear until after her first death, and Takagi and Yamamoto don't act very enthralled, more disinterested and jealous respectively.
Tomie is a daemonette of Slaanesh.Tomie is often described and interpreted as a Succubus, a daemon whose career is the seduction of innocent males. She can appear to her host as whatever they considered to be the most beautiful being in existence. However, it is emphasized that daemonettes do not really want the well-being of their hosts in mind, only pleasure, and driving their hosts to obsession and in the end the brink of insanity, as per the will of Chaos.
- The only problem with this theory is that the Emperor would already smite her down if she really was a Daemon. The Emperor has been silently watching over mankind long before the age of strife.