After the great escape from Bergen town,the trolls dulled or lost in color due to the passing of the king, and presumably his eldest daughter, they scattered and fended for themselves or stayed in small groups.
Poppy was found by King peppys friend, thorn, in the tunnels, and he raised her by himself for years, teaching her how to survive and fend for herself.
[note : thorn is an oc of mine for this story]
With the Brozone not splitting up when they did, the brothers also escaped with the rest and ended up building the ''underground-hideout'' that their baby brother branch wanted