Channeling (Sexual) Emotional Energy
A person or device collects energy from (sexual) emotions. Could be a good excuse plot for a masturbation scene, if somebody needs to provide the energy for whatever reason (or it's their job). Or a good excuse plot for any form of casual sex scene, if one of the partners is (knowingly or unknowingly) collecting energy from their partner. Could make good BDSM or NonConsensual if one partner doesn't want to provide the energy and the other wants to get it by any means necessary.