During the winter (shortly after Fiona receives her letter from Atlas), while she and Jormungand are...um...unwinding after a long difficult day in the lab (I honestly expect a lot of canoodling to be going on this season), she will ask if he knows Greek.
Followed almost immediately by [color=blue]"Jormungand, what are you doing? No, get away from there! I'm serious!"
Since he doesn't (afaik) speak or read Greek, she will then start asking around the covenant. Probably starting with Helmut, since (presumably) he tends to rave about the boy.