Cuthbald's Farm is the closest of the outlying farms to Thrymm's Farm, where those working the farms were supposed to meet should the outlying farms be attacked. Oter made it there and is worried because his brother Ragnold has not yet arrived.
'With the farms being attacked by Warg-riders, I expected my brother to be here by now. He works on Cuthbald's Farm, which is just to the south-east of here. I think I see black smoke rising in the distance from that direction!
'I want to go look for him, but if Warg-riders are there I will be in as much trouble as he is. Can you help me find out what happened to him?
'I need just a moment to collect myself before we go. Here, take this horn and summon me when you are ready to go, and I should be ready by then. Use the horn down the road south of here, and I will catch up with you.'
Oter asked you to call him over to you on your way to Cuthbald's Farm. On the road south of Thrymm's Farm is likely a good spot to summon him.
Now that he is with you, speak to Oter before heading to Cuthbald's Farm.
Cuthbald's Farm is south-east of Thrymm's Farm.
Oter's brother must be on or around Cuthbald's Farm somewhere. With Wargs and Warg-riders around he likely didn't make it far.
Oter's brother was trapped under debris, but appears to be all right. He looks eager to leave Cuthbald's Farm quickly, but would like to speak to you first.
Oter's brother, Ragnold, has gone back to Thrymm's Farm. You should speak to Oter about saving his brother.
Since his brother has been saved and has safely returned to Thrymm's Farm, Oter will be eager to speak with you there.