when do we find out about titus being a red

In Red Rising , you find out Titus is a Red during the Part 3 reveal, when Darrow talks with him in the cellar and realizes Titus is one of the same hidden people he is. The clearest breakdown in the sources points to Part 3, chapters 27–33 , with the actual realization happening in that confrontation.

What happens

Darrow goes down to speak with Titus after the House Mars conflict, and Titus’s story and hatred make Darrow realize he is not just another Gold; he is a Red disguised as Gold. That discovery is the turning point, and it leads directly to the decision that Titus cannot be allowed to live.

In plain terms

If you want the shortest answer: you find out right before Darrow kills Titus. The reveal lands as part of the punishment scene after the battles in the House of Mars storyline.

Spoiler note

This is a major spoiler for Red Rising , so if you are still reading, that reveal is one of the book’s big early shocks.