Ruby is a soldier Gem in charge of guarding Sapphire when Blue Diamond's Diamond Royal Court arrived to Earth. She fused with Sapphire by mistake, and it was this that had her flee with Sapphire. She joined the Crystal Gems after agreeing to being a perma-fusion as Garnet.
Ruby has bright scarlet skin, burgundy irises and dark burgundy, square shaped hair. She is slightly taller than Steven and has a thick build.
She wears a maroon and brown tank top and a matching maroon headband tied around her hair. Her ensemble also includes mid-thigh burgundy shorts, and short, pointed maroon boots similar to Amethyst's. Her gemstone is located in the palm of her left hand and has a square facet.
Ruby has been shown to be the emotional side to Garnet, and more willing to show how she feels than Sapphire would. She is a Gem of action, and will get into situations regardless of what fate would have for her, being the driving force, strength, and courage that makes Garnet decide which future vision would be taken. According to Sapphire as well, she's the one who did most of the actual fighting while as Garnet. She also has a sense of self-value, possibly due to her being a guard, as she responded "who cares?" when Sapphire asked if she was okay.
Ruby holds a deep care for the other members of the team, especially towards Sapphire in particular, and when calmed down shows a sort of playful side to her. Still, she does have a short temper, and can and will go off on a tangent with little provokation, seeing situations more on the surface than what Sapphire would see. This rage can make her logic a bit cloudy at times, and can make her especially harsh if pushed too far, most evident after Sapphire had been captured by White Diamond, and her anger towards Flint as a result of her stress. This is something carried onto Garnet as evident when she yelled at Pearl.
Despite her bravery, this is mainly for when she knows what'll happen. In a situation where she isn't in control or doesn't know what to do, she becomes more humbled and nervous, as shown during her time with the Ruby Squad.
Ruby was once assigned as a guard towards Sapphire. When Pearl and Rose Quartz attacked the royal court, she tried to protect Sapphire, and in a desperate attempt, she ended up fusing with Sapphire, forming Garnet for the first time. She seemingly left the diamond court with Sapphire sometime afterwards, and during a walk through a forest, she and Sapphire ultimately decide to stay as a perma-fusion.
Ruby ended up coming out not long after Steven Universe became corrupted, due to how stressed and freaked out she was on the situation. she and Sapphire found Sombra with them, and she ended up not only poofed, but cursed as well. When she came back, she found that her body was not in her control, making her do backflips, bow to Sombra, and clean his horseshoes, all not to her own will. She constantly tried to defy him during this, and she was used later on to curse Luna to form Nightmare Moon. She was used as Sombra's personal guard during this whole fiasco, and at one point, Sombra orders her to try and shatter Sapphire. She finally broke free when she tore off her arms, the curse itself seeping out of her, and she got herself free. She regrew her arms shortly afterwards, and managed to form Garnet once more.
During the later stages of the Galactic Ray mission, she came out with Sapphire, as Sapphire wanted her to train Peridot herself instead of as Garnet. Ruby tried to get some other candidates for it, but in the end she got picked either way. Ruby went on for the next few days training Peridot (arguments notwithstanding), when the Giant Bird attacked them both. Ruby tried to fight it, and desperately tried to save Sapphire, almost jumping off of the Sky Arena, only to be saved by Peridot. Desperate to save her, she and Peridot went to the Strawberry Battlefield, fighting the bird once more until they poofed it, only after the fact finding her alright. She fused with Sapphire after this.
Homeworld Arrival Arc
On Homeworld, Ruby had to stay behind in Blue Diamond City as Sapphire, Lapis Lazuli, and Rarity went to the Abandoned Gem Settlement, making her very stressed out as she waited, wondering what was happening to her. She got into another fight with Peridot, resulting in a pillow fight for a little bit until she realized how dumb that was. She and Peridot began to play a few games until found by Blue Pearl. She fused back with Garnet once Sapphire came back.
During a game of pretend with Steven, Peridot, Sapphire, and Emerald, Ruby joined the others in spying on him in Bayburgh, her disguised as the "street smart girl". She followed him into Bull's Eye Books n' Vids, exploring the store as they were there, and then following him to the local market. She got a bit upset when Sapphire and Emerald were talking, thinking he was flirting with her, but she calmed down quick after a kiss on the cheek. When it started getting late, she insisted on getting Steven home, though convinced to stay when they would've been mugged if they did go home at that moment. She went to Seaside Hotel for the night until Emerald brought her and the others to the party. She returned to Beach City the following morning.
After an argument over Camp Pining Hearts, Sapphire ended up tricking her into fusing with Peridot instead of fusing with Sapphire, first becoming Rubidot. She at first objects, but soon found it pretty enjoyable, and even asked her to stay as her a little longer.
when the Ruby Squad arrived to Earth, she was asked by Sapphire to go with them after being shown a vision of Leggy getting eaten by the Nuckelavee Monster. She went on and played along with the team once they arrived to the Tunguska Gem Facility, and she ended up leading the party down inside at Doc's command. She went with Leggy and Navy for the first half of the exploration, learning of their overall goal as she was with them. When the group got back together, she quickly stopped Army from hurting Leggy, insisting that they move on. As they went through the Gem experiment room, Army used her and Leggy in a visual aid for what was inside one of the experimental tubes. After that, she went with Leggy and Army to the storage hold. She kept Leggy company and comforted her throughout the ordeal. On hearing the monster, she summoned her Gem weapon, Army growing curious as none of them ever had a Gem weapon like hers, before the monster confronted them. She saved Leggy from getting eaten, and got eaten herself, only for her to heat up and poof the monster from the inside out. She freaked out when they start to get suspicious of her, but Eyeball points out that she saved one of their own, getting her out of trouble, and letting them bring her back home.
Ruby and Peridot join for a snow sculpture by Rarity when they got word of a strange event in Beach City. When The Blue Light occurred, Ruby was ready to fuse with her, only to be pushed away as it seemed unnecessary, much to her confusion. She went with the group to Ronaldo Fryman, as much as she didn't want to, and learning of Starlight Glimmer's possible involvement. Before going after though, Buck Dewey got her to split up the group and she went off with a few others to get Sapphire, just to find her getting captured by White Diamond.
Angry and freaked out, she went straight back to everyone else and calling the emergency to their attention. When Flint suggested not to go, she refused to listen to him and went as far as to punch him, knocking him off his feet, and screaming at him and calling him selfish and horrid, ironically making him more motivated on the situation. She was tasked as Lapis's soldier as part of Flint's plan upon arriving to the White Diamond Space Station, and she of course went with Team A to get to Sapphire. She didn't manage to fuse back to Sapphire until after they got released in the throne room, and after Sapphire was healed.
Ruby appears during Harmony Day to help out the preparations of the house. When hearing the explanation for the mistletoe, she immediately jumped in and tried to get a kiss from Sapphire herself after seeing her kiss Peridot.
Ruby appears again after being forced apart when dropped into Discord's dimension. She tried to keep everyone calm during the entire event, though when she found out of Discord's reason, she was ready to fight him in her anger, though she was stopped later when shown the evidence.
Upon learning the truth about Pink Diamond, Ruby and Sapphire forcefully split up. Ruby tried to calm Sapphire down, only to be harshly pushed away by her. Angry and distraught, she herself revealed the truth to everyone else before Pearl could explain properly, causing everyone, including her, to run away.
Ruby was found on Brooding Hill with Greg Universe, Pinkie Pie, and Fluttershy, coming to terms with what Sapphire told her, and realized she was correct about someone else telling them to be together. She concluded she was always with someone, and wanted to go out on her own much like how Flint would do. This drove her to behave like a "cowgirl" after some inspiration, and went to the Badlands with her friends to fulfill this desire. That night, she and Steven went off on their own, only to find the Changeling Kingdom, and soon become prisoners to Chrysalis.
While trapped inside, Ruby revealed she couldn't truly stop thinking about what Sapphire would want, missing her a lot and feeling alone. She finally learned about the future by The Spirit when she fell asleep, waking up in her dreamscape. Alongside Steven, she promised to make things right, and save everyone, forming into a fusion with Steven upon awakening.
Ruby and Steven were split up later on when a Windigo found them, leaving her exposed and forced to fight them. During the fight, she went with Steven and Connie Maheswaran to save Chrysalis, saying she's saving someone for reasons she doesn't quite understand. when unable to save her, she decided to stay with the fallen Windigo. Sometime later, she returned with the Reformed Windigo as her steed, and stopping the Pony of Shadows from hurting Connie, and her fire was what revived Steven. After the fight, and the Pony of Shadows defeated, she proposed to Sapphire.
During the wedding, Ruby revealed she never thought herself highly just by herself, but felt more important with Sapphire, and vowed that nothing will ever come between them again. On Steven's pronounce, she and Sapphire fuse into Garnet.
Ruby's signature trait is her ability to control fire, or at least heat up to high temperatures. This is mostly linked to her emotions, as when she becomes angry, her temperature rises. The angrier she gets, the hotter she becomes, resulting in smoke coming out of her body at times.
When used with the Reformed Windigo, it has a healing property added to it, described as the fires from the Fire of Friendship.
A trait passed onto Garnet in the form of her gauntlet launchers, Ruby has shown that her physical body can still survive, albeit shortly, when her Gemstone is removed from her body, and is capable of bringing her gemstone core back onto her sometime later.