Posted my Primarch & Legion. 

In Gorseval's history, he fought a brief battle against the forces of the Grim Crusade before the Emperor finally forced Gorseval to surrender. Does anyone feel like having their Legion being part of the expeditionary force that accompanied the Emperor, and subsequently having fought against the soldiers under Gorseval's command? Some of those soldier still survive as members of the Void Stalkers' Black Guard, and I think it'd create an interesting dynamic.