Cactus Steven initially resembles a cutting of an ordinary cactus with a dark green hue. He eventually takes on the features of his creator, Steven, upon introduction to his magical spit. These features include eyes, a mouth, and hemispherical bumps similar to the shape of Steven's hair.
With prolonged exposure to Steven's anger, Cactus Steven takes on a lumpy, deformed appearance. He grows much larger and begins to don a physique similar to his creator's, eventually sprouting several Steven heads, two torsos, multiple limbs, and, eventually, pink flowers.
He appears to copy what Steven does. Initially, he is friendly before slowly becoming more and more angry and hostile when Steven dumps his emotions on him, culminating in him physically attacking Steven and the Gems. He later forgives Steven for his actions and leaves the Beach House.
Cactus Steven is created accidentally by Steven Universe when he absent-mindedly places his healing spit-covered finger on it after being pricked by a normal cactus. Steven finds the next day that it has come to life, to which Amethyst then names him Cactus Steven.
Steven later talks to him on the beach and Cactus Steven starts to repeat what he says, especially his inner thoughts and doubts. He does this in front of the Crystal Gems, which leads Steven to hide him away from them. Steven continues to rant on about his frustrations about his life and the Gems, causing Cactus Steven to grow.
Eventually, he grows limbs and escapes the greenhouse to attack Steven. Steven and the Crystal Gems retaliate, which causes him to grow to a gigantic form with multiple heads and limbs. The Crystal Gems are outmatched in combat, while he continues to repeat Steven's frustrations towards them.
Steven realizes that Cactus Steven is just continuing to mimic him. This realization leads Steven to end the fighting by offering an apology and giving it a hug, which causes Cactus Steven to sprout flowers. Cactus Steven gives Steven one of the flowers before busting out of the house and running off.
Steven is the creator of Cactus Steven. At first, he is endeared by his creation and discusses his life's problems with him. He is delighted when Cactus Steven starts talking, but this quickly turns to anger when he starts repeating Steven's complaints about his life. Steven grows more and more annoyed, as does Cactus Steven, culminating in Cactus Steven growing into a humanoid shape and attacking his creator. Steven fights back with few qualms, only feeling guilt when he slashes through his creation's shoulder with his shield.
Steven realizes that he is responsible for Cactus Steven's violent nature and hugs him, despite the intense pain involved in doing so. Cactus Steven returns the hug, growing pink flowers in the process. After this, he departs, leaving Steven feeling very guilty over his treatment of his creation.
- Enhanced Durability: Cactus Steven is formed from the Earth's most resilient plant according to Garnet, allowing him to withstand a number of attacks from the Crystal Gems during his rampage. He can also rapidly regenerate any damage and grow in size with additional limbs and heads. Severed limbs can attack on their own.
- Needle Generation: Being a cactus, Cactus Steven's entire body is covered with a protective layer of needles, which can be utilized for both defensive and offensive purposes. Direct attacks to his body or any sort of physical contact will result in his attackers being painfully stuck with needles. Cactus Steven can also shake off the needles to attack from afar. Should Cactus Steven lose any body parts, the severed limb will briefly inflate like a balloon and burst, subsequently spraying its needles all over as a result.
- Water Absorption: Another natural ability, Cactus Steven could absorb a great deal of water. By doing so, his body can grow to a massive size and sprout additional deformed limbs, regrowing any previously lost to injury. The water from a running sink faucet enabled Cactus Steven to gain extra arms, another foot, and several more functional heads.
|1. "Little Homeschool":||Absent|
|3. "Rose Buds":||Absent|
|6. "A Very Special Episode":||Absent|
|7. "Snow Day":||Absent|
|8. "Why So Blue?":||Absent|
|9. "Little Graduation":||Absent|
|10. "Prickly Pair":||Debut|
- Cactus Steven shares similarities to the creature of the novel Frankenstein.
- Both creatures are initially innocent, only to later become angry after being mistreated by their creators. Both eventually forgive their creators (the creature from Frankenstein doing so after realizing that the death of his creator didn't bring him happiness, and Cactus Steven doing so after Steven apologizes for his mistreatment towards him.)