|“||I wouldn't have payed any attention except... well, it was Luke.||”|
–Juniper, in The Battle of the Labyrinth
Juniper lives near Zeus' Fist (the pile of rocks at Camp Half-Blood), and stays within her tree most of the time, watching the Camp. She also hates dogs because, in her own words, she "knows about dogs and trees." Juniper and Grover start dating sometime between The Titan's Curse and The Battle of the Labyrinth.
Juniper is first seen while she was attending Grover's trial by the Council of Cloven Elders, being comforted by Clarisse and Annabeth. Later, she tells Percy that she saw Luke entering the rock where the Labyrinth's opening is in camp, near her tree. She also recalls seeing Quintus doing the same thing. Juniper warns Percy not to trust Quintus.
During the battle, her tree almost gets set on fire and Percy stops the fire that was damaging her tree, and she joins the battle after that. She also uses a "Whipping Stick" in battle.
In the Demigod Files, Grover seems to say that the tree nymphs were so beautiful and then remembered that he was dating her, so he asked them to edit that part out, or Juniper would kill him.
Juniper calls Percy to a meeting with Leneus and Nico, telling him that Grover has disappeared, and she is very worried and heartbroken. At this meeting, Nico is embarrassed and blushes when Juniper puts her hand on Nico's arm. Percy soon finds that Grover had been entranced into a deep sleep by Morpheus and wakes him. Grover is frantic about what Juniper must have gone through while he had been missing for two months and says she is going to kill him, and hurries back to camp. Juniper is very worried about Grover during the battle at olympus, but luckily, he survives.
In celebration of Grover's birthday, Juniper frolicks with the nature spirits of Long Meadown in Prospect Park, Brooklyn while Grover and Percy Jackson sit on a nearby bench, watching. Their day is interrupted when Apollo arrives to assign a quest to Percy and Grover.
Juniper is a very sweet wood nymph, and is very loving towards Grover. She is usually worried for Grover and is jealous of his liking of other wood nymphs. When Grover was in an enchanted sleep, she wondered why he was gone so long and is worried that "he might be with another tree" and that "he once had a crush on a blueberry bush."
Juniper is small and petite, with wispy hair the color of amber, and a pretty elfish face. She wears a green chiton and sandals, and is said to be a very pretty girl. When Juniper blushes, her skin turns green with chlorophyll, instead of red, her eyes are green and when she cries her tears are green.
Although Juniper's life source is tied to her Juniper bush which usually limits her to the vicinity of Long Island (where the bush is located) Juniper is able to take short trips away from home as long as she keeps a handful of Juniper berries inside her pocket.