I put "Straight" in quotations because the characters would say, and believe, that they are straight, it would take a suggestive moment or mistake(which may or may not happen, I'm half pantsing half outlining) to make them question. The two women are: a mans wife, and a mans favored slave/concubine. (I know this looks like it belongs in the erotica section, but the intention is to add flavor and drama, and is not a major plot point). The MC (the slave/concubine that escaped) is generally annoyed by the wife. The wife is a scheming alpha that takes advantage of weaker people, somewhere between lady Macbeth and Seska from ST:VOY. She is annoyed by the MC because the MC was prized by her husband. Since the MC left, it would just be easy for the wife to dismiss her, However she at one point commanded the gunman not to shoot her as she escaped, and showed up at her cabin one day to tell her the cost of her escape, and to give her a heads up that the husband would be coming for her. My question is, how would I show this to the reader, that there is a subconscious (or just back of conscious) sexual tension between these two women?