you were once Human, but you were bitten by a hellhound and as Sam and Dean found you they decided to spare you, one day you sit in the back of the Impala while Dean is driving and Sam's looking at the map and you try to get some shut eye but then Dean speaks

Dean: "So puppy, you figure out how to control your powers yet?"

Sam stops Dean

Sam: "Dean stop it, it's only been a few days since they got bitten"