Picture or animation containing two characters. Thou shalt count to two. No more. No less. Two shall be the number thou shalt count, and the number of the counting shall be two. Three shalt thou not count, nor either count thou one, excepting that thou then proceed to two. Four is right out. Once the number two, being the second number, be reached, then, thou shalt add this tag.
Not to be confused with romantic_couple.
Note that for tagging purposes tentacles only count as a character if they are attached to a visible creature (octopus, etc.).