In the excerpt read at RR apperance in NYC, the old lady June mentions Percy losing his mark of Achilles, how, when, where, why will he lose it?

I am warning you now: This will DEFINITLY NOT be voted as best answer, as it stinks.
How: No idea
When: In this book...end of series...?
Where: No idea.

I told you! Actually, I didn't know that was possible. Maybe only a god can take it away...? I don't know, Rick Riordan always finds a way! ;)

Well anyone remember the old myth where Jason(the original one!) carries an old 'crone' across a river and once he crosses to the other side she turns into Hera! I believe the same thing is happening to Percy but Hera's Roman aspect; Juno. Anyway I remember somewhere that "June" tells Percy he will lose his curse once he crosses the river into Roman territory.

*shrugs*

We'll see as soon as The Son of Neptune comes out, hm? I'm planning on finding the answer to this tanong the araw the book comes out myself.

I really don't know. I hadn't heard about it until a few days ago, and I'm confused too. Don't feel bad. *pats shoulder*

June is I think Janus .. He gives Percy tWo options one to carry him ( June ) to the roman camp or leave hi here alone . But he warns Percy telling him that if he takes hi. To camp , Percy will lose his curse of ACHHILES ... Man now Percy is a good guy he takes Janus to camp and loses his curse ..
I hate RR for doing that !!! Arghhh !!!

PS Janus is disguised as an old lady called June

Basically if he forgets his anchor (Annabeth) he will lose the curse. Because he won't remember anything for what I know and Annabeth was what kept him alive in the Styx. So he will forget the curse ever happened and the anchor that keeps him alive. Boom it's suddenly gone. Another way is that he could become a god.

I'm not sure how or where, but I am sure it will happen sometime in SoN. If you look at the cover, Percy has a scratch on his cheek. I don't see any other reason why that would be there.

Well i think Percy is losing the sign becuz
1) he in the roman side
2)he getting hurt alot
3) or the river magic is were off