A couple that switches between dominant and submissive roles, sexual or not.
This can involve any sexual act and does not require anal or vaginal sex, but it is the most common depiction.
Especially in yaoi, a reversible couple will top and bottom for one another. Hetero and yuri couples may make use of a strap-on to achieve penetration.
Different roles for each character can appear in:-
This tag does not apply to images where a character tops and bottoms with different individuals.