"Cerberus"

the legend states that there is a guardian keeping watch at the gate of the underworld, Cerberus is what they are called., however unlike the stories it is not a three-headed dog but three separate dogs who are clinging close together and work in unison. these three brothers (Cerb, Beru, Erus) still keep going the underworld and are much calmer than the beast in legend, one day they get too curious for their own good and decide to sneak off to the overworld.