Spawny

Spawny is a Rabbid that appears in Mario + Rabbids Kingdom Battle and Mario + Rabbids Sparks of Hope. In the Mushroom Kingdom, he is differentiated from other Rabbids by his white muzzle, his blue belly and ears, the fused SupaMerge headset that covers his eyes, and the power button on his lower back. His ability is to fuse other beings with Rabbids; however, said power is uncontrollable, and it activates whenever he is stressed.

Spawny's name is given to him by Bowser Jr., who seeks to use his powers to take over the Mushroom Kingdom. Although he is a major catalyst for the events of the game and forms an alliance with Bowser Jr., Spawny is not truly evil.

History
Spawny starts out as an ordinary Rabbid, but when he and many other Rabbids are transported to the Genius Girl's laboratory, Spawny steals the SupaMerge and uses it to fuse other Rabbids with objects, doing so to create Rabbid Peach and Rabbid Mario. When Spawny enters the Mushroom Kingdom, the SupaMerge ends up meshing with him, turning him into what he looks like throughout the game.

Beep-0 informs Mario that the SupaMerge had been corrupted upon entering the Mushroom Kingdom, and he agrees to find Spawny. However, just as Mario and co. are about to catch Spawny on a tower overlooking Ancient Gardens, Bowser Jr. appears and befriends Spawny. Mario and co. traverse the three other worlds and eventually defeat Bowser Jr. in his mech, Mecha Jr., retrieving Spawny in the process as well as reuniting with Yoshi. However, the portal over the Mushroom Kingdom releases a dragon named the Megabug, which captures Spawny and harnesses his power to unleash more beings. Mario and co. end up defeating the Megabug and freeing Spawny and Bowser (who had also been corrupted by the Megabug). Spawny is then seen in the pre-credits scene, where he admires the statue erected in honor of Rabbid Peach.

Spawny appears with Bowser Jr. at the beginning of Donkey Kong Adventure, where he fires a beam at the Time Washing Machine after Rabbid Kong enters it, causing it to close.

In Mario + Rabbids Sparks of Hope, Spawny is mentioned to have worked with Beep-0 to create the WM ARC spaceship, but not seen. He is set to appear in the game's first DLC, The Tower of Doooom.

Personality
When he is still a regular Rabbid, Spawny is mischievous, curious, and playful like his fellow Rabbids, while always causing trouble without thinking about the consequences. After his transformation, Spawny becomes timid, naïve, and childlike. Spawny has little to no control of his abilities, so even Bowser Jr.'s persuading him to use them often did not help.

Relationships
Bowser Jr.: Bowser Jr. takes an instant liking to Spawny, quickly befriending him and even being the one to have given him his name. At first, Spawny feels comfortable with Bowser Jr., choosing to tag along in his Junior Clown Car. However, Bowser Jr. harnesses Spawny's talents in an attempt to defeat Mario and co., knowing his father would be proud of him for doing so. In the process, this leads him to intimidate Spawny to get him to activate his powers, leading Spawny to feel increasingly distant. Despite that, Bowser Jr. does care about Spawny, showing great concern when he falls out of his Junior Clown Car as well as scolding at Mario and co. when he is kidnapped by the Megabug later on. After Spawny is safe, thanks to Mario and co., Bowser Jr. gives him to the heroes, relieved that he is safe and apologizing for putting them in harm's way. In the end, Spawny is comfortable around him as with everyone.

Mario, Luigi, Princess Peach, and Yoshi: Spawny is initially uneasy around Mario and friends, fearing that they are his enemies. Spawny is startled when he and Luigi wake a Piranha Plant, and it scares him, causing him to create the Pirabbid Plant. Throughout the game, Spawny grows uneasy around the heroes, causing more stress, but eventually comes to realize they want to help. After the battle with Mecha Jr., Spawny falls out of the Junior Clown Car and is saved by Yoshi. After being rescued from the Megabug, Spawny eventually befriends the group and settles down. He seems to be the closest with Princess Peach as his trophy shows her hugging him while he smiles, and she even holds him during the unveiling of the Rabbid Peach statue. In an artwork of them, Spawny is giving the princess a holographic mustache, much to her surprise.

Rabbid Mario, Rabbid Luigi, Rabbid Peach, Rabbid Yoshi, and Rabbids: Before his transformation, Spawny treats his fellow Rabbids with compassion and mischief. After his transformation, he becomes timid and shy around them. With the heroic Rabbids, he is afraid of them because he thinks they are his enemies, but he eventually warms up to them, seeing them as his friends.

Trivia

 * Spawny's mask is meant to be a reference to the Studio Ghibli film .
 * In the Spanish version, Spawny's name is revealed by Beep-0 after Toad reunites with Toadette in Ancient Gardens before Bowser Jr. names him in Top Banana.