Before The Lightning Thief
While most satyrs he was sent to find demigods and to protect them. Due to his failure at rescuing all of the 3 demigods under his care, he was deemed a failure. While Grover claims the failure as his fault, Thalia later on reveals that it was in fact Luke.
Grover befriends Percy at Yancy Academy. Percy is mentioned to hav though Grover had bee held back a few yrs due to his facial hair and acne. On a field trip Percy pushes Nancy Bobofit with his godly powers after she throws her lunch at Grover.
Percy is then goes with Mrs. Dodds who turns into a fury, Percy then slays her and after doing so discusses this with Grover who pretends to not know about her like the others are doing. Percy though sees that Grover is bluffing due to his hesitation.
Percy later hears Grover talk to Mr. Brunner about him.
After Percy loses Grover, Grover tries to find him and eventually tracks him to Montauk beach where Percy and his mom are on vacation. He then warns them and they travel to Camp Halfblood, on the way Grover reveals he is a satyr and is knocked out and Percy’s mom “dies”. Percy then defeats the Minotaur and drags Grover into Camp Halfblood.
At Camp Halfblood, Grover tells him that he fears he will not get his Searcher’s Liscense to find Pan due to his failure to bring Percy and his companions to camp.
Soon Grover is to go with Annabeth on Percy’s quest to go to the Underworld and recover the Master Bolt.
Before the departure, Luke gives Percy a pair of flying shoes which Percy gives to Grover due to his being forbidden to travel by air.
Along there trip they meet the Furies once again, face Medusa, and Percy and Annabeth retrieve Ares’ shield from Waterland a nearby water park. Once retrieving said shield, Percy then finds out that his mom didn’t die but was rather kidnapped by Hades. They are then give transport to Las Vegas.
While traveling to Las Vegas , Grover gets really upset by the harsh treatment to the animals in the smugglers’ truck
In Las Vegas they check into the Lotus Casino where Grover is seen playing a shooting game where the animals are shooting the hunters. There danger isn’t known until Percy realizes the Casino is a trap and when they escapes they realize they have been there for 5 days.
They the face a giant and after defeating him they travel to the Underworld, and get past Cerberus.
When near Tartarus, Grover’s flying shoes begin to drag him toward it and he barely escapes. They the confront Hades who has lot the Helm of Darkness and it is soon revealed that in Percy’s backpack, the Master Bolt has been and after vowing to get his Mom back, Percy with the others travel to Los Angeles where Ares(who is revealed to be the one to put the Master Bolt in the backpack) is defeated and the Helm is reclaimed and given back to Hades.
Percy then takes the bolt to Zeus and says that Kronos is awakening.
Grover is given his searcher’s license at the end.
Sea of Monsters
For most of the book he is captive of the cyclops Polyphemus who thinks Grover is a female cyclops.