The Vampire Diaries, Season 4

Silas:
[in Elena's form] Don't bother. I'm not in there anymore.

Stefan:
Silas. You were stone. They saw you. The spell worked.

Silas:
That's the funny thing about spells. They're bound by nature, and nature demands balance, so every spell has a loophole. The spell that turned me to stone was bound by a witch, a living witch, so when that witch died, the spell broke.

Stefan:
Bonnie. Bonnie's not dead.

Silas:
Doesn't matter, does it? And here's where the mystery of me comes full circle. I created the immortality spell 2,000 years ago. I could never die, so nature needed to find a balance, a version of me that could die. A shadow self; a doppelganger.

Stefan:
So this is finally your real face? You're another one of them?

Silas:
Not exactly. Hello, my shadow self.