What you want

Vikings, some combination of Ragnar/Athelstan/Lagertha. NC-17. Dirty talk, light D/s, masturbation, shame.

Also at AO3.

Fill for my own prompt from dirty_kinkmeme. Warning for use of the "C" word for female genitals.

( Ragnar catches Athelstan jerking off and watches him while talking dirty about what Athelstan would like to do to Lagertha. )