There’s nothing in BDSM which precludes someone who identifies as a dominant from being the bottom in a piercing scene, nor is there any reason why a slave might not be in an entirely satisfying relationship as someone’s dominant or top.

Note that we’re not talking about switches here. What we’re talking about here are BDSM roles. We can define a role as a set of attitudes and behaviours which determine how we interact with our partners and which of our collective wants and needs we can meet and how we meet them.