LogFAQs > #894945603

The Delta twist is actually probably the most well foreshadowed end game twist of all 3 games. There's a reddit post that lists like 80 different instances of foreshadowing before the reveal, its actually kind of impressive.

The only thing that makes it kind of dumb is no one ever calls Sean 'Sean' before the reveal but that's at least a little bit more believable than Sigma never once touching his face in VLR and noticing there was a massive bionic eye on him.

EDIT: Probably my favorite foreshadowing is when Sigma and Diana are stuck in the shelter together, when Diana has Delta and Phi, if you check the status screen during this it will list both Phi and Q as alive despite listing them as dead until that happens.