If you play through the game’s end as Mors and choose the dialogue option “I will care for him, for Jeyne’s sake,” when Varys brings Jeyne’s child to the throne room, you unlock Mors’s first epilogue. As promised, you take the boy east across the seas, far away from the troubles of Westeros.
You are taking care of Jeyne’s son as if he were your own, though you have your doubts on how someone who knows only violence and death could ever make a good father.
Just then Dog hears something. You grab your sword and slowly walk out to meet the threat, whether it be the Night’s Watch hunting you down for desertion or assassins out to kill the boy who is a threat to the throne back in King’s Landing. The life you’ve chosen will be one always on the run, protecting Jeyne’s son until he is old enough to protect himself.