I was reading some things off the internet and i was thinking she must be the Mole or something.Because of her late appearance to the show.

I was thinking the same thing.  I like how they brought in the League of Assassins or League of Shadows since it's on Cartoon Network.  Who was the young woman in the mask that lead the attack?  Was that Cassandra Cain, I think she's no longer Batgirl and has joined up with the League of Assassins?  I love Young Justice, so much better then the old Teen Titans.

 http://www.imdb.com/title/tt1830446/
 
artemis is currently a spy for the light. though so people know, she is not arrowette as most speculated. dc has said she does know arrowette though. if i can get links to what i found, i'll post again.

The woman with the mask on was Cheshire...and I figured Artemis was the spy, though I have a feeling that, that might change as the series goes on. Hopefully the characters that they kill aren't part of the young Justice group, they are far to awesome...plus they are better than the Teen titans in my opinion. And I did read that there were going to be main character deaths somewhere. Hopefully it's just rumor.