Last fall, Mr. Janetti, a TV writer in Los Angeles whose credits include “Will & Grace” and “Family Guy,” began posting photos of Prince George and other members of the British royal family with made-up captions.

In Mr. Janetti’s hands, Prince George is a jealous, insecure tyrant, with a cruel hatred for anyone who upstages him, especially Ms. Markle. He criticizes her wardrobe choices, her career as an actress, her insurgent presence within the closed ranks of the royal family. After her engagement to Prince Harry was announced last November, Mr. Janetti had Prince George reminding her, “There is ONE star in this family.”

While readers of People and other celebrity publications see images from a real-life fairy tale, Mr. Janetti’s 300,000 Instagram followers are being given a dark fictional drama — “Game of Thrones” starring an imperious toddler in short pants.

Speaking by phone recently, Mr. Janetti explained how he came to create what he called “a Shakespearean play for our times as told through Instagram,” and what he has in store for the royal wedding.

Are you a royals watcher? Is that how this started?

No, I’m not a royals watcher at all. I saw pictures of George’s first day of school. He had such an expressive face. I thought, ‘I’m going to write from his point of view.’ That was the genesis of it. It started very simply.

I did a post. It got nothing. It wasn’t until I paired him with Meghan Markle. I did a mash-up of them side by side. People responded instantly to that. Then I saw how much fun I could have with…