User blog comment:SayuriDarling/The Mark of Athena Official Discussion/@comment-4515675-20121005151408/@comment-5112532-20121005212123

Maybe they got tortured in there, and get a similair mark? Slightly pessimistic, I know!

I know, her dagger... waaahh! Even after, RR told us the background story to how Luke got it and gave it to Annabeth. I bet you, that a monster in Tartarus becomes impaled by it (it's a long way down..) and she is able to reclaim, or has to fight to the death with it...