Fuldak's House can be found in UnderBrǎgon.
Fuldak Thanesson lives near the Iron Wall Barracks. He helps the troops by buying in potions and assisting their recovery from battle injuries. Recently he paid a travelling alchemist 250gp for 25 potions of healing, but they are all producing random effects in his patients. He still has 22 left and he can’t use them! If you’re willing to help he’ll start you on the Noxious Concoctions quest.
Fuldak has a family, his wife Bertha, a son Thǎne Fuldaksson and a daughter Helthi.