RSP had the sectum sempra sequence of the film.. and they wanted something that could also represent that "spell" since it was such a big deal in the book. The simple idea of a blood splatter across the chest and the words in a font that looked like slytherin, was won over by all! There were 3 colors to choose from and the baby T's for the ladies. At first we were concerned that Warner Brother's would not approve a "violent & bloody" design, but they were totally cool with us moving forward with it.