On the midseason finale of The Vampire Diaries, Stefan asked Katherine to prove that she's worth loving. Or at least not killing.
Her response was an attempt to help Stefan protect Elena and it boiled down to this: follow up on Isobel.
Does this mean Mia Kirshner will soon reprise her role as Elena's birth mother? It sounds that way, based on what producer Julie Plec told TV Guide:
"Isobel has a lot of information and will continue to be useful for that information," executive producer Julie Plec tells us. "Where she is right now, what she's doing and whose side she's on - those questions start to get asked very soon."
If Isobel does return, she might be reunited with an ex-lover. It's already been confirmed that David Anders will appear in 2011 as Uncle Father John.