I called it, "Chain of Command".
The notion of a BDSM group hierarchy is not uncommon in kinky stories. And the genders of the three people involved can be as different as our tastes, but for me the crucial element has to be that there is a clear chain of command that does not waver. There is a Top who is dominant over everyone, a sub, and a 'switch' who is subordinate only to the Top but dominant over the sub.
Since psychology in dominance and submission is such an exciting element to me, I have often pondered the various permutations and combinations of this arrangement. For my own tastes, the Top is never male, but he can be the switch. Still, I prefer fantasies where, like the drawing, the male is the sub, or where all three are female.
In the past I have pictured fantasy scenarios with people I know and challenged myself to imagine what it would be like if X was my Top and then Y topped X. Plugging different names into X & Y resulted in a myriad of emotional responses in me......from exciting to disturbing. Sometimes if I knew someone who came off as decidedly submissive, I might imagine myself in the middle of the chain, but more often than not, I'm at the bottom. For a kinky mental exercise, it can be interesting and fun to ponder.