“Grover, you're the bravest satyr I ever knew.”

Grover is usually cheerful and upbeat, yet he chews on furniture when he is nervous. He cries when he is upset, which makes him an easy target for bullies. He can often be philosophical. He sometimes mopes around a bit though. He has an obsession with coffee (due to feeling the presence of Pan in New Mexico while drinking it), tin cans, and enchiladas. He believes that cheese enchiladas are better than chicken ones. This may be due to the fact he is a vegetarian. His girlfriend is Juniper, a wood nymph. They deeply care for one another. It is also revealed in The Last Olympian that he has leporiphobia, (which Percy calls his "bunny phobia"). He and Tyson don't seem to get on very well but he is helped looking for Pan by Tyson in The Battle of the Labyrinth. It is mentioned in The Lightning Thief that two of the only songs he knows how to play on his reed pipes are "So Yesterday" by Hilary Duff and Mozart's 12 symphony. In the beginning of the series, his reed pipe music is so bad it makes the strawberry plants try to strangle people, but by the end of the series, he can play multiple tunes (which came in handy multiple times). It is said in The Demigod Files that his favorite song to play is Muskrat Love.

Grover is afraid of many things. He is most terrified of:

• 
  Underground places (which smell of death and monsters)
• Cyclopes (which is why he initially did not get along well with Tyson.)

It was also mentioned that he has leporiphobia (fear of rabbits) and describes them as "big bullies who always steal celery from defenseless satyrs." He is also terrified of Dionysus, Juniper's anger, and ghosts. He cries when he is upset, but it seems that he has grown out of this.