I'm kind of lost with the Theon plot, who's that guy fucking with him?
I'll tell you if you really want to know, but as mentioned earlier, the show seems to be written that we're not supposed to know who he is, just as Theon doesn't. Highlight the white text below if you want to read the clues from previous episodes (I don't especially consider these spoilers, it's just what's happened), PM me if you want a straight answer/can't be arsed to work it out from the clues.
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(1) You can actually figure out who he is (well, everything apart from his name) by the events that happened the last time we saw Theon in s2. Especially a comment the lad's father (yes, he was in s2 and has been in s3 already) made to their leige lord.
(2) There is a pretty big clue in the method of torture that the unidentified lad is using. His father mentioned it to their leige lord in an early s2 episode. It's a family tradition you might say.
(3) There is a massive visual representation of his house's sigil in Theon's dungeon. Or rather the sigil was taken from what's happening to Theon. We've seen the sigil flown by a group of riders this year, and they serve Theon's torturer's father, who we've already met.
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Basically what we know is that the dude is the son of one of Stark's bannermen, Karstark (the one who Robb just beheaded, but he apparently doesn't know this yet), his brother was killed by Jaime,
Wrong.
When he said to Theon "You forgot to ask if I'm a liar" he was referring to telling Theon that he was right. Theon had not guessed right, and still has no fucking idea where he is, or who it is that's torturing him. I doubt he'd have let him go even if Theon
did/does guess right, but on this occasion he was fucking with his head by letting think he'd guessed it. He hasn't.
Right.