Luci is this three weeks old bat's name shortened Lucifugus is the whole word she wasn't used to flying outside the cave of her bat family yet and mistakened Poppy as a moth. Luci is a nice young bat who lets Poppy stay in the cave while her bat family goes hunting. Then Luci lets Poppy meet her mom, and later Poppy meets their leader Oldwing.  Luci and Oldwing try to explain to Poppy why they they rarely have visitors. But at the end the of last book it's also Luci who led her family to the mice when everyone needed to run away from the quickly spreading fire caused by a lightning strike touching a tree, and Luci is even willing to take Poppy and her family to their new home at the end of the story.