Pumpkin

Pumpkin is a sentient pumpkin created by Steven for Peridot and Lapis Lazuli in "Gem Harvest". Pumpkin is currently living at the barn.

Appearance
Pumpkin is a small pumpkin with four legs, two pumpkin seeds for eyes, a carved mouth to bark out of, and a stem for a tail. Pumpkin also has a tongue made of pumpkin guts with pumpkin seeds for taste buds.

Personality
Pumpkin's personality matches that of a regular dog, being capable of barking, jumping, and rolling around on the ground, and is happy and playful in general. Pumpkin treats its owners with great loyalty and affection, but responds negatively when threatened, as it turned to Peridot and Lapis for comfort upon seeing Steven carve out a different pumpkin. Pumpkin was also willing to help out Peridot, Lapis, and Connie at the car wash in "The New Crystal Gems".

"Gem Harvest"
Steven felt bad for Peridot and Lapis living alone at the Barn, so he licked a pumpkin seed and planted it in the ground. The next day, it transformed into Pumpkin. Initially, Pumpkin was loyal to Steven, similar to his Watermelon Stevens, until he gruesomely carved another pumpkin in front of it. After this event, Pumpkin shows the same amount of loyalty to Peridot and Lapis instead. Pumpkin is later seen being chased by Amethyst who shapeshifted into it. Pumpkin appears to be afraid of Steven, as it runs away in terror when seeing Steven wielding a knife. At the end of Andy DeMayo's visit to the Barn, Peridot is even shown trying to teach Pumpkin how to say "clod". Pumpkin also spits out the groom figurine from the wedding cake used at the family dinner, having swallowed it earlier, something which disgusts Andy.

"The New Crystal Gems"
Pumpkin arrives at the Temple with Peridot and Lapis, looking through a laundry basket. Later on, Connie holds it, and Pumpkin is given the role of Pearl on their new team. As Pearl, Pumpkin wears a party hat over its nose to match Pearl's pointy nose. It helps dry off the cars at the car wash with Connie, and occasionally barks throughout the episode.

"Room for Ruby"
Pumpkin can be seen running around the barn. Pumpkin licks Navy like a dog when the latter appears to be nice, and is shown to be concerned when Navy tricks the Gems. Pumpkin accompanies Steven, Peridot, Lapis and Navy throughout the episode.

Steven Universe
Being created by Steven, Pumpkin initially loved him, and would not leave his side until Steven carved a pumpkin in front of it. For quite some time afterwards, Pumpkin has both hated and feared Steven. However, near the end of "Gem Harvest" and in "The New Crystal Gems" it appears to be fine with him. In "Room for Ruby", Pumpkin happily greets Steven and allows him to hold itself when the four of them swim to shore after being tricked by Navy.

Peridot & Lapis Lazuli
Pumpkin loves Peridot and Lapis, living with them in the barn and acting as a pet or roommate to them. When Pumpkin fled from Steven and jumped into Peridot and Lapis' arms, Steven remarked that it was nice for them to have "a new addition to the family". Although the full extent of their relationship is unknown, Pumpkin has been seen listening to the two of them, and cuddling in Lapis' arms. They are close enough for Peridot and Lapis to bring Pumpkin to Steven's house when they are told to protect Beach City in the Crystal Gems' stead.

Amethyst
Pumpkin seems to like Amethyst, as it is seen playing with Amethyst who is shapeshifted into its likeness. Although the full extent of their relationship is unknown, Pumpkin is shown to be comfortable enough to rest in Amethyst's arms before fleeing in fear at the sight of Steven holding a knife, after which Amethyst tells it to "chill out, dude" and chases after it to presumably calm it down.

Connie Maheswaran
Although the full extent of their relationship is unknown, Pumpkin has been shown to be comfortable around Connie, as it rests in her arms.

Trivia

 * The pronouns used for Pumpkin interchange depending on the speaker; Steven refers to it using He/Him pronouns, while Peridot refers to it using She/Her pronouns.