no you don’t get it this is revolutionary. guillermo has been tied to nandor for so long because he wanted nandor to be the one to change him. he’s been his familiar and his bodyguard and taken care of him with everything he has. but nandor refused to change him because he thinks guillermo would leave after, that that’s all guillermo has stayed for. so guillermo is now reasserting his autonomy and his desires above nandor’s insecurities, and if derek does change him and guillermo returns to the house (which he implied he’d do by saying “nothing ever changes in this house unless i change it) then that will confirm to nandor that guillermo wants to be there. even if derek doesn’t change him, this is a huge moment for guillermo because he’s recognizing that he doesn’t need nandor to get what he wants.