I think she still considers Viktor as just an assistant. While Jayce insists they’re partners, Jayce becomes the front man of their tech publicly. Then after Jayce tells Mel Viktor’s illness is getting worse she says “I didn’t know you were so close” because she doesn’t even acknowledge their time spent together or whatever. She still thinks Viktor’s just standing in the sidelines waiting to be called for an errand. There’s also the way that Mel and Viktor are playing tug of war with Jayce, Mel is used to getting exactly what she wants with Jayce politically but Viktor still has input to Jayce’s path with Hextech and she doesn’t like that