So basically protagonist is sidekick of hero
They go to defeat evil
Protagonist becomes sidekick of bad guy

The Turning

Reversal

But it was predicted by an old lady

How the Turns have Tabled

You have to have a title that alludes to another plot point. Sp the reader THINKS they know where the title came from, then BAM.

Face Off

Seer?

The Sidekicks

Forseen

The Flip Side
Heads or Tails

Unexpected

The Masks of a Sidekick

Altered

Dats a good tip timebender
But I also like it when they finally realise what's going on and they're like "That's why the book is titled that!"

Bruceman