S1: Whatever the Case May Be

When I was watching this episode I remember waiting an extremely long time to finally see a flashback.  Unfortunately, there was a lot of cat and mouse on the island with Kate and Sawyer before the viewer got to see some pre-island Kate.  

Kate was not being a good girl.  She spearheaded an operation to rob a bank for a tiny toy plane.  She reveals to Jack that it belonged to the man she loved...the man she killed.

So recap - Kate is bad yet she has a conscious and only killed/shot the bad guys in the bank and she got her tiny toy plane that was the only thing on her in Sydney.  We also get a little more flirtation between her and Jack and Sawyer developing the impending love triangle even more.  Overall, it wasn't a very strong episode, but that's expected when Kate is the focus.