In which episodes of ABC's Quantico does Caleb Haas' alter ego Mark Raymond appear? I'm a little confused about the plot and want to go back and rewatch his storyline.
Caleb Haas' alter ego Mark Raymond appeared in many bits and pieces
First it was shown in S01E02 ending:
Through his Facebook account with the name Mark Raymond.
In Later episodes we also see his mail account with same name - src
But his alter ego directly appeared first in S01E08 near the ending and again in S01E14 around 11:13, and in the same episode Will confront him.
And Will and Caleb get into good terms in S01E16 about the secret and Will even dress similar to him to join the Fanatic group in S01E18 but it backfires and Caleb try to save him by going in Mark Raymond look in the end of episode. In S01E19's second half Caleb complete his whole mission as Mark Raymond against those fanatics and tell Shelby the whole story with bit contradiction to his father's version of story but it seems Caleb told the truth, even cleared by his conversation with his father.