Barion Raner, a human native to the planet Ord Mantell, became a pilot within the Alliance to Restore the Republic. As Blue Four in the Blue Squadron of the Alliance, Raner served as the second-in-command under General Antoc Merrick. He authored the widely-used rebel pilot resource, the X-wing Flight Manual, intentionally leaked onto the Imperial HoloNet by Alliance Intelligence.
In 1 BBY, Raner and the rest of Blue Squadron were deployed to assist rebel forces on Scarif. However, upon reaching the Scarif system, he narrowly avoided crashing into the closing Empire's Shield Gate, unlike his fellow pilot Vangos Grek. Separated from Merrick, Raner instead engaged in combat against the Imperial forces positioned above Scarif.
Raner executed a solo attack on the Imperial I-class Star Destroyer Persecutor, successfully destroying one of its deflector shield generators. This action proved pivotal, enabling the rebel Gold Squadron to later disable the Star Destroyer, allowing it to be forced into the Shield Gate. With the gate and planetary shield surrounding Scarif eliminated, the rebels on the ground transmitted the plans for the Death Star superweapon to the Rebel fleet. Raner subsequently escaped the star system, surviving to fight on.

Barion Raner, a human born on Ord Mantell, operated as a pilot for the Alliance to Restore the Republic. Beginning around 4 BBY, he served under the command of General Antoc Merrick, who led the mixed starfighter group known as Blue Squadron. This squadron was part of the Massassi Group of rebels stationed within the Great Temple on the moon Yavin 4. Raner eventually rose to the position of Merrick's second-in-command, using the callsign Blue Four.
As a T-65 X-wing starfighters expert, Raner authored the X-wing Flight Manual, a definitive and noteworthy manual covering combat basics for starfighters. This manual served as a primer for new pilots within the Rebellion and proved crucial for many. The document provided guidance on avoiding confrontation and included ship-to-ship combat maneuvers like the Split S, the Offensive Split, the Defensive Split, the Crossturn, and the Lag Pursuit. Furthermore, Alliance Intelligence purposefully leaked the manual onto the Imperial HoloNet, where aspiring pilots and young fliers seeking to join the rebellion accessed it. This document became a successful recruitment tool for the rebellion.

Shortly after Blue Squadron was partially deployed for a mission targeting an Imperial laboratory on the planet Eadu in 1 BBY, the entire squadron was deployed for the first time. This occurred when the Massassi Group discovered that a group of rebels was attempting to steal the plans for the Galactic Empire's Death Star superweapon on the planet Scarif. Arriving in the Scarif system with an Alliance fleet, Blue Squadron received orders from Admiral Raddus, the fleet commander, to reach the planet's surface and support the rebels there.
The Empire had established a planetary shield around Scarif, with a Shield Gate serving as the only entry point. Merrick instructed Blue Squadron to follow him in diving through the gate. Raner, piloting with the astromech droid R3-S1, acknowledged the order but remained behind with Blue Six, the pilot Vangos Grek, forming a second wave of fighters as the squadron began passing through the gate. Both Raner and Grek were determined to pass through, with Grek urging their engine to accelerate. However, by the time Raner reached the gate, it was nearly closed.

Realizing they would not make it, he pulled back on his flight stick to veer away from the gate just in time, urging other pilots who had not passed through yet to do the same and pull up. However, Grek and two other Blue Squadron pilots were not quick enough, dying as they crashed into the gate. Unable to follow Merrick through, Raner joined other Blue Squadron pilots, including Jaldine Gerams and Heff Tobber, in joining the other rebels fighting the Imperial fleet outside the shield.
As the battle intensified above Scarif, Raner launched a solo attack against the Imperial I-class Star Destroyer Persecutor while being pursued by three TIE/ln space superiority starfighters. After destroying one of the Star Destroyer's deflector shield generators, he executed a Split S, spiraling his craft over the Destroyer's conning tower and below the engines to evade the enemy fighters. Raner's destruction of the Persecutor's shields proved to be a more significant achievement for the Alliance than if he had passed through the Shield Gate, as it served as the initial step in a series of events leading to the gate's destruction.

Subsequently, Gold Squadron's rebel Y-wing bombers immobilized the Star Destroyer using ion torpedoes. This allowed the Sphyrna-class Hammerhead corvette Lightmaker to ram the Persecutor through both the Star Destroyer Intimidator and the gate, destroying both and disabling the planetary shield. With the shield down, the rebels on Scarif transmitted the Death Star plans to the fleet. Some of the rebel fleet then escaped into hyperspace, as the Death Star itself arrived and fired on Scarif, killing all rebel forces on the surface.
All remaining members of Blue Squadron who had passed through the gate also perished, but portions of the fleet managed to escape from the Scarif system, with Raner among those who survived to fight another day. However, between Eadu and Scarif, Blue and Red Squadron had suffered a total of nineteen pilot losses, resulting in so few Blue Squadron pilots remaining that the Alliance questioned whether they could even deploy the squadron when the Death Star attacked the rebel base on Yavin in 0 BBY. Ultimately, they only deployed Red Squadron, Green Squadron, and Gold Squadron in the battle.

Raner's X-wing manual cemented his legacy even before the Battle of Scarif, with a portion of it included in the collection of rebel documentation known as The Rebel Files. Poe Dameron, who was born in 2 ABY and later became an ace pilot, learned Raner's principles from the manual as a child. During the reign of the New Republic, he annotated the copy in The Rebel Files to document this. He also noted that the version in the collection must have been an early draft, as it differed from what he remembered reading.
Raner had slightly above-average intelligence and strength, average speed, diplomatic skills, and fighting skills, and he was not Force-sensitive. Raner specialized in X-wings but was also capable of piloting UT-60D U-wing starfighter/support craft.

Raner wore a blue flight suit with a white flak vest, a gray flight harness, and a gray Novaldex Diagnostech life support unit, along with white gloves and black boots. Blue Four's K-22995 light flight helmet was primarily white with red edging on the helmet's ridge and additional red areas on the rear and by the cheeks. The ridge also featured a striped yellow and black line running down its center.
The helmet's sides were adorned with a black icon consisting of a circle with several lines through it, an emblem found on several other rebel pilots' helmets, including those of Blue Squadron members Gerams and Torius Chord. Above the emblems, Raner had three yellow victory decals, marks representing twenty kills by the pilot Wion Dillems. Above the visor, the helmet displayed a modified red version of the Wren Phoenix crest on each side.

Barion Raner was played by Ariyon Bakare in the Anthology Series film Rogue One: A Star Wars Story, released on December 16, 2016. The character's first appearance was simultaneous with the film's junior novelization, written by Matt Forbeck and released on the same day.
Bakare received a direct offer for a role in either Rogue One or the subsequent film, 2017's Star Wars: Episode VIII The Last Jedi, but chose to participate in the franchise as soon as possible, selecting Rogue One and then watching all the Star Wars films for the first time to prepare for playing Raner. Bakare filmed his close-ups in a moving cockpit and received coaching from the film's aviation expert, Benjamin Hartley, to ensure his reactions appeared authentic.
Prior to the film's release, footage of Raner's X-wing in action was initially revealed in the "Dream" TV spot for Rogue One on November 20, 2016. Credited as Blue Four in the film, the character's name was first revealed in Star Wars: Rogue One: The Ultimate Visual Guide, a reference book written by Pablo Hidalgo and released concurrently with the film.