What the spell says is pretty irrelevant to that. Sure, Wren doesn't know - and hasn't said - that she ever thought the spell was cast on her, but ... she knows Iclyn. Bardic magic is not some obscure secret so "Someone plays music out of nowhere, person you've known for years suddenly abandons what they're doing to act uncharacteristically towards the one playing the music" is a fairly simple line of reason to follow.<br/><br/>The spell means you don't know that a spell has been cast on you, it has nothing whatsoever to do with explaining away the pretty obvious effects it has on others.<br/><br/>As for the slavery - Isabella is a slave. That has been made pretty clear. You have a slave = you are a slaver.