DISCLAIMER: Your Steps and Tasks may be different
Gronyr wanders the roads outside Prydwen Keep and stops at the stone in the road that says Camelot. He also stands near the entrance of Prydwen Keep and some times near the farm house where the zombies spawn. If you hail him, he will warn you about the zombies that have taken over his farm. The farm is near the road and if you wait until night time, the farmer will spawn along with a pile of other zombies. Killing the farmer gets you some nice gloves. Killing the zombie sows will sometimes get you a rotting hog tail. Give the tails back to Gronyr and he will give you a cloudy green stone (worth about 50 copper) for each one.
Gronyr wanders, sometimes he is in Prydwen Keep to the left of the entrance, sometimes on the road by the Camelot stone, and third place is next to the rock next to the stables at the farm.
Gronyr Gloyw says, "Help! Evil is walking the land and it has despoiled my farm. An army of [zombie swine] has invaded my land, they are led by the walking corpse of the farmer who owned the land before me."
Gronyr Gloyw says, "Aye, foul and corrupted undead swine rise from the ground at [night] and dance around their unholy master, a zombie farmer. If you bring me rotting hig tails as proof that you have killed them, I will reward you."
Gronyr Gloyw says, "Only at night do the beasts rise from the grave to ravage my fields. Even if you do not agree to help me, beware walking the road near m farm at night, for evil walks the land."
After killing a zombie sow, give the hog tail to Gronyr Gloyw.
Gronyr Gloyw says, "Thank heavens, one less monster to ruin my land. Here is a small payment for your troubles."
You receive a cloudy green stone from Gronyr Gloyw!