Sasuke and Orochimaru in “Unfinished Business”

Sasuke

Trying to unlock the mysteries of nature, you toy with people's lives for the sake of this vain and ridiculous cause of yours. [reflects on Itachi massacring his clan to measure his power] You disgust me. [Orochimaru reveals his true form, a giant snake] The giant white scaled snake. Never would've recognized you. So that's your true form. In order to keep switching from body to body, you experimented endlessly and this is what you've become.

Orochimaru

Now Sasuke you are mine. Give me your body!

Sasuke

A snake that crawled on the earth dreamt of soaring through the sky, knowing full well it was impossible. Still hoping beyond hope, it kept its eye on a baby bird that it nurtured in its own nest, little realizing that... [activates his curse mark's second level and grows wings] That snake is now the prey because that bird is a hawk... ready to take to the sky!