Here are some ideas for people writing Primarch/Reader.
A Primarch has a child somewhere out there—one he didn't even know existed. Naturally, he needs proof.
But then he hears that very child cussing someone out in exactly the same way he used to when he was a teenager. "...Alright, that’s definitely mine."
+ bonus if Sanguinius and Roboutes kids cuss in very very street kid way. It just funny as fuck.








