Stop doubling down. The story is literally telling us she was the one to coin the term for him. "Bu- but, the mage and the ot-" Shut the fuck up. Clearly the story is talking about before even that. The story said he found out she coined it for him. It doesn't say she joined in on calling him that after he left, it doesn't say that she defended him, it doesn't say that the others called him that again. The story says that she started the "Parasite" thing.
"But the elf is ni-" Shut the fuck up. She's a selfish, two-faced bitch. The story clearly establishes that too. Maybe re-read everything instead of going off memory if you're having this much trouble keeping up.