According to creator Eric Kripke, the show originally was intended to focus on the weekly monsters, with Sam and Dean Winchester merely being "an engine to get us in and out of different horror movies every week". His sole desire was to merely "scare the crap out of people". However, a few episodes in, Kripke and executive producer Bob Singer noticed the onscreen chemistry between Jared Padalecki and Jensen Ackles. This revelation caused them to change the series to focus more on the brothers than the monsters, basing the weekly monster around the storyline they wanted for the Winchesters. According to Kripke, "... sometimes we don't even have the monster until way late in the break, once we get all the angst and the drama done first."