Apothecary Oni'jus is a forsaken, who was once a half-elf, in the Undercity. The forsaken queen initially chose two brilliant minds to lead her new Apothecary Society. The first was Faranell and the second was Oni’jus, a half-elf infiltrator who was a master of mundane poison concoction (and whose idea it was to add “Royal” in front of their fledgling group’s name).
Oni’jus was one of Prince Arthas’ infiltrators before the war, having an uncanny ability to ferret out the prince’s enemies (even the ones he was unaware of). She considers it her greatest failing — and the one she paid the highest price for — that she failed to see the prince’s deterioration in front of her. She fled his side before his embrace of Frostmourne in Northrend, but fell to the plague on her way to warn Lordaeron.
The strong will she developed as an infiltrator allowed her to keep mostly free of the Scourge’s control, and she willingly followed when Sylvanas called. Oni’jus’ poison and assassination skills are invaluable to Sylvanas, and the queen appointed the half-elf to lead the Testing department of the Society, sending teams of warriors and rogues out to capture mortals and Scourge alike to test the vile toxins she and Faranell create.
She is dedicated totally to the destruction of Arthas and the Scourge. Vain of her fair looks in life, she enshrouds her decomposing body in swaths of black cloth, which helps her conceal herself in darkness. No one knows what she looks like under her yards of protection; only her glowing eyes show.