User blog comment:FairyRaven/Fairy Tail Chapter 467: Mother's Key, Review and Commentary/@comment-1359322-20160104115124/@comment-49.151.112.92-20160105035111

Why do you assume it was Jacob Lessio behind Marin trying to kill Brandish? That man was with God Serena and August face-to-face with the remaining Four Gods of Ishgar and Jura at the eastern border of Fiore far away from Magnolia for crying out loud.

It's theoretically impossible for someone like him to be manipulating Marin from that far just to kill one of the Shields of Spriggan who is capable of toppling countries all by herself. And I think Marin just did it in his own free will as payback towards the harsh treatment she had done on him.