Subtext

There's been some discussion of subtext among my fellow writers. I'm speaking in terms of the second definition from Collins English Dictionary.

subtext, n
1. an underlying theme in a piece of writing
2. a message which is not stated directly but can be inferred

I ran across an excellent example while watching Inspector Morse. Here's the setup:

Mary married Trevor, the oldest son in a wealthy, traditional family. Mary has been having an affair with her husband's younger brother, Steven. A few days after Trevor's murder, Betty, her sister-in-law, shows up at Mary’s house. Mary answers the door. They are both the outsiders in the family.

Betty: I thought about phoning but then I thought, well, that was the easy way, so . . . here I am.
Mary: Do you want to come in?
Betty: How are you bearing up?
Mary: Alright. Don’t think it’s sunk in, yet.
Betty: Family rallying around?
Mary: Yes, everyone’s been very kind.
Betty: Good. If Stephen and I can do anything to help, then you will let us know, won’t you?
Mary: Thanks. You’re very kind.
Betty: We wouldn't want you to be alone, unless of course you prefer it. One of us could stay with you if you like.
Mary: No. No, that won’t be necessary.
Betty: You sure you don’t want me to send Steven round. I mean he could sleep on the sofa or something. Just until you've over the worst of it.
Mary: I wouldn't dream of imposing on him. He’s got enough on his plate as it is.
Betty: He wouldn't mind. He can sleep anywhere. It makes no difference to him. Shall I lend him to you for a while?
Mary: Dangerous. I might want to keep him.
Betty: I don’t think so. He is very unreliable, you know. A lot of unexplained absences.

The solution is left as an exercise to the reader.