It's believable. From this episode you can see that VV clearly does not like Marianne. Specifically how he kept referring to Lulu has 'Marianne's child' and how he raged when he found out the reason for Jeremiah's betrayal was Marianne. And then when the emperor finds out that VV had sent assassins after Lulu, he says that he had been lied to again.
VV turning out to be the major villain and Charles being completely innocent of everything Lulu's accused him of would be a good LOL PLOT TWIST