R2-C4, often called "C4," was an R2 series astromech droid that served the New Republic during 34 ABY. As part of Kazuda Xiono's squadron, R2-C4 participated in their mission to get intelligence concerning the First Order to the Resistance. The mission was threatened when Major Baron Elrik Vonreg, a pilot in the First Order, launched an attack on the squadron. Mia Gabon and Hugh Sion, both members of Xiono's squadron, managed to escape to hyperspace before Vonreg struck Xiono's X-wing, where R2-C4 was stationed. Fortunately, Commander Poe Dameron of the Resistance arrived just in time to rescue Xiono and R2-C4. By working together, the members of the New Republic and the Resistance commander were successful in driving off the First Order pilot and fulfilling their mission. After Xiono decided to join the Resistance for a mission on Castilon, R2-C4 stayed with the Resistance.
R2-C4, who was also known as "C4," was a New Republic astromech droid that was active roughly thirty years following the Battle of Endor. R2-C4 went along with a New Republic squadron, under the leadership of pilot Kazuda Xiono, on a mission to give intelligence to Commander Poe Dameron of the Resistance. R2-C4 was situated in the astromech socket of Xiono's T-85 X-wing starfighter. The squadron that Xiono led was ambushed by Major Baron Elrik Vonreg, a First Order TIE Fighter Pilot. Xiono informed R2-C4 that he was unsure of Dameron's location but felt confident he would be there soon. Because of the danger, Xiono ordered the rest of the squadron, including pilots Mia Gabon and Hugh Sion, to go back to base while he delivered the intel.
After Gabon and Sion had left, Vonreg managed to hit Xiono's X-wing with a shot. Xiono asked for confirmation that his squadmates had successfully jumped to hyperspace and reacted positively to R2-C4's confirmation, but then realized his X-wing was losing power. Dameron then appeared to save the New Republic pilot and droid by destroying approaching warheads and drawing Vonreg's attention. Xiono then told R2-C4 to give him control of the weapons. Xiono then asked Dameron to lead the First Order pilot in his direction. Dameron maneuvered Vonreg toward Xiono and then moved away to allow Xiono to fire and damage Vonreg's TIE. Vonreg was then forced to retreat before Dameron could finish him off.
With the battle concluded, Dameron told Xiono to come aboard so the Resistance could repair his ship. A CR90 corvette then came out of hyperspace, which Xiono and R2-C4 boarded. They met BB-8, a BB unit, and Dameron while onboard. Dameron left to speak with General Leia Organa, and a flustered Xiono requested Dameron to say hello to Organa for him. The droids then made comments to each other, and Xiono asked them to stop and show him where the refresher was. While Xiono was in the refresher, BB-8 went to talk to Dameron, which Xiono found out after he left the refresher. Xiono asked R2-C4 which way BB-8 went, and then insisted he would look around. He told R2-C4 to stay put, but the droid ignored his order.
Xiono agreed to join the Resistance, and Dameron assigned him a mission on Castilon. R2-C4 was left with the Resistance, where he became a member.
Industrial Automaton was the manufacturer of R2-C4. The droid had a blue chassis, along with gray, white, and yellow plating. The droid's dome had a light blue sensor on it.
The first picture of R2-C4 was in a trailer that introduced Team Fireball, along with concept art of Kazuda Xiono. R2-C4 was in "The Recruit," the first part of the two-part episode that was the premiere of the Star Wars Resistance television series, which premiered on October 7, 2018. The episode only referred to R2-C4 as "C4," but the 2019 reference book Ultimate Star Wars, New Edition gave him the full designation of R2-C4.