It's been over two months since Shining Armor and Princess Cadance arranged a rather... taboo understanding with their rehabilitated former enemy, King Sombra. Even though the former Tyrant no longer wishes to reclaim his throne, or even think to return to his wretched past, his lust for power made him a perfect suitor for the married couple's debaucherous desires behind closed doors. But despite how sadistic and demeaning Sombra may be around Princess Cadance, Shining couldn't have felt more content with the position he allowed himself to be in.

Unfortunately, one particular weekend might prove to be a bit more daunting for the submissive cuckold of a Prince. For you see, it seemed that Sombra and Cadance arranged for another mare to join in on their fun. And just like the first Princess Sombra had claimed as his own, his second is somepony just as close to Shining as his own wife...

His sister, Princess Twilight Sparkle~

[NOTE: This story is the winning sequel from my December Commission Poll on my Official Patreon page, and is a NSFW prompt that involves M/F/F sex, cuckolding, power-play, shared oral, voyeurism and exhibitionism, humiliation, degradation, incestuous pegging, and lots of marital taboos. Reader Discretion is Advised.]