Seraphim derive their name from the highest choir of angels in Christianity, those who are allowed to attend the throne of God, which in turn derive their name from the Hebrew word seraph, meaning "a burning, fiery state."
Usually, Seraphim appear as angels from myths all over the world, composed of pure energy. Others take more elemental forms; twisting columns of fire, pulsating orbs of light, crackling motes of electricity, and so on. Often, crackling and roaring energies herald their presence.
Each Seraph stands steadfastly for what it believes to be just and right, and is typically a skilled warrior for whatever its distinct cause may be. The forces that Seraphim command are generally used for benevolent purposes, but that is not to say that they cannot be destructive. Indeed, if an entire city must be demolished for the sake of what a Seraph understands to be the greater good, he would not hesitate to (and, in some cases, could very easily) burn it to the ground. Seraphim, like all Supernal Angels, are not creatures that are capable of recognizing grey areas of morality.