Dean is turned into a ravenous giant. Sam is powerless to stop his big brother's endless rampages. (Or the one in which Dean is horrible to everybody else, but has a soft spot for his Sammy, although his perception of morality is screwed.)
Ethan and Grayson Dolan are not only twins, but giants. Ethan, unlike Grayson, does not like eating humans. Grayson, on the other hand, is a cruel, ruthless pred that doesn't give much thought to the way they live. (Vore. Giants. Dolan Twins.)