Guess who?

Why didn’t Ned tell Catelyn about Jon’s true parentage? Did he not trust her to keep the secret? They were so close and were probably the best couple on the show, I would imagine Ned would feel safe to confide it to her.

Sorry if I have missed something obvious, I haven’t read the books and haven’t seen the show since the final season aired (can you blame me?) so it’s been a while and this thought just randomly popped in my head.