Reidoth is the druid the party was sent by Qelline to find as he might be able to tell the party where Cragmaw Castle was located. Asked the party to help chase away or kill a young green dragon that was residing in a nearby tower in Thundertree. Let the party sleep at his camp the night before the battle.
After the party vanquished Venomfang at Cragmaw Castle, they returned and he gave them a Bag of Holding as promised, and in addition a Grey Bag of Tricks since they actually managed to kill him. Told the party they would most likely not see each other again as he was soon moving on for a while since Thundertree has been cleansed... for now.
After a few months, Reidoth assisted them in getting quickly from Tempervale to Maplemere, and then later onwards to Hala's corrupted shrine to take down the hag once and for all. He also helped Demetrius return to Cantalos to seek knowledge of his mother's murder, leaving the party.