Hello,
for those who want to find out by themselves how to talk to vendors when in Vampire Stage 4, please do not go further in this discussion.
For the others (and I hope some fellow dev passing by), I think I have found out a bug.
My character is a Vampire constantly in stage 4. So I use the Mesmerize/hypnotize skill to seduce all kind of merchants to get to trade with them.
Except for the Bags merchants, I was able to trade... But for those, I tried countless times and it seems not to work (I tried several ones in Davon's watch, Solitude, etc...).
Is this an expected behavior or is this an issue where the bag merchants were not added to the "seducable list" of NPCs (I imagine it is something like a boolean variable on the class that was not set to true).
K.R.