<P> Nathan Riggs is introduced in the sixth episode of the show 's twelfth season as a new cardio attending at Grey - Sloan Memorial . It is quickly learned that he and Owen Hunt ( Kevin McKidd ) had been friends , but that their friendship ended acrimoniously . It is later revealed that Nathan and Owen 's feud was caused by the disappearance of Owen 's sister , Megan . Megan , who had been engaged to Nathan at the time of her abduction , had discovered Nathan 's infidelity before running off and ultimately getting kidnapped . Owen has long blamed Riggs for the fate of his sister , who has been presumed dead for 10 years now . However , as time goes on , Nathan and Owen learn to work together and eventually tentatively reinstate their friendship . </P>
<P> Nathan Riggs is introduced in the sixth episode of the show 's twelfth season as a new cardio attending at Grey - Sloan Memorial . It is quickly learned that he and Owen Hunt ( Kevin McKidd ) had been friends , but that their friendship ended acrimoniously . It is later revealed that Nathan and Owen 's feud was caused by the disappearance of Owen 's sister , Megan . Megan , who had been engaged to Nathan at the time of her abduction , had discovered Nathan 's infidelity before running off and ultimately getting kidnapped . Owen has long blamed Riggs for the fate of his sister , who has been presumed dead for 10 years now . However , as time goes on , Nathan and Owen learn to work together and eventually tentatively reinstate their friendship . </P>
how do owen and riggs know each other
how do owen and riggs know each other
had been friends
had been friends