Snape had nearly finished his explanation, when he drew Harry’s attention to the first bottle, "This substance I shall administer myself once every two weeks - its healing properties are extremely potent, but short lived if handled improperly," Harry, now well used to Snape’s routines when attending to his neck, didn’t need to be asked to pull his shirt collar apart to expose the angry, barely healed scar that curved from his collar bone up to the back of his ear.