All that is known of Midnight Express' early years is that he is a California native and that his mutant powers surfaced during puberty. Finding regular life dull and boring (and incredibly slow thanks to his superspeed), Joshua left home and dropped out of school at age 16. Using his computer skills and superspeed he forged himself a high school diploma and hacked into the UCLA computer system to register himself for classes, majoring in computers and electrical engineering.
Joshua's university career didn't even last a full year. He again became bored and dropped out, this time choosing to work his way up and down the California coast. It was during this period that he met Rita DeMara. He honed his electronics skills doing part-time work for Scott Lang (Ant-Man II) and became friends with Scott and his daughter. He eventually wound up in San Francisco doing occasional footwork for the detective agency run by Jessica Drew (Spider-Woman I). It was in San Francisco that Joshua was invited by the mysterious Raven to join the government sponsored super-hero team, the Dark Force.
Eager for the excitement that being a super-hero promised, Joshua signed on to the team. Knowing the propensity for mutants to be associated with the letter X, Joshua took the code-name Express. When he saw the rest of the team, and the proliferation of black in their respective outfits, he designed a black and silver outfit for himself and changed his hero name to Midnight Express. (note: due to the level of anti-mutant hostility on the part of the public, and the government for that matter, Joshua gave his name as Justin Masters for the Federal government's Mutant Registration database). Being by far the most mentally stable member of the Dark Force, Midnight Express kept the group from degenerating completely into a grim, violence-prone bunch of vigilantes. At least he did until a fateful mission to Japan ended with Chaos' hypnotic programming kicking in, Phantasm being apparently killed, Raven being critically injured, and Night Breed being possessed by a Central American demon. In the aftermath Midnight Express and the American were the only team members to make it back to the US with their hides intact. At that point the team was effectively gone. Rather than recruit others, Val Cooper chose to cancel the project completely (though she apparently has kept an eye on Joshua ever since, covertly helping him now and then, and turning to him and his teammates in the Cavaliers for help on a few occasions).
While the American remained in San Francisco, Midnight Express made his way south. During a stopover in San Diego he, and a handful of other local heroes, became involved in a battle with members of the Masters of Evil. Actually, Express became involved in the battle because he saw Flare heading to investigate and decided to follow the "gorgeous flying babe," but that's not important. What does matter is that the heroes were victorious and they decided to form a team, thus were born the Cavaliers!
Midnight Express has been with the Cavaliers ever since and has probably been the most publicly visible member of the team. Never one to shy away from the spotlight, Express is usually the one giving the sound bites for the media. He gets along with all the members of the team, and is especially close to Faultline, each considers the other to be his official "sidekick"; and Flare, a fellow California valley-child and the object of his affection (or at least one of the top three in the category). He also has a friendly rivalry going with Wild Ryde for position of "Cavalier with the most hero experience."
Personality-wise Midnight Express appears to be pure California valley-child, i.e. never takes anything seriously and shallow as a Death Valley mud puddle. In truth, Express is quite intelligent, despite an attention span measured in nanoseconds, and he takes his position as a hero very seriously. On several occasions Joshua has risked his life to save others. But Express is still a teenager at heart and enjoys having fun as much as the next dozen guys. Among his noteworthy accomplishments are the creation of the hyper-caffeinated beverage known as the Midnight Espresso and an ongoing crusade to have worn more costumes than the Wasp.
Midnight Express is a mutant whose reflexes are superhumanly fast. As a result he can run at several times the speed of sound and reacts to stimuli approximately 150 times faster than the average person. This has caused some friction with members of the Cavaliers since a number of the video games in the Cava-lair have been rewired by Joshua to work at more reasonable speed (to him). To enable him to survive moving at these high speeds, Midnight Express' body is several times denser than a normal person, which has the added bonus of making him slightly more resistant to damage than most people. Josh has also learned to focus his superhuman speed into his metabolism, the net result being that he can heal most non-fatal injuries in a fraction the time (and it makes him very hungry).
On top of his superhuman speed, Midnight Express has the ability to affect kinetic energy in his immediate vicinity. Basically, this means he can ignore Newton's Laws of Motion and do things that would have Sir Isaac spinning in his grave (a feat M.E. could in fact accomplish but its way too morbid for his tastes). Since this power affords him control over such things as his own momentum and centripetal force, it allows Midnight Express to perform such seemingly impossible stunts as coming to a dead stop from full speed in an instant, making hairpin turns at any angle without changing speed, and altering the speed and direction of nearby objects. Among the neater tricks he has learned is causing an opponent to suddenly change direction (usually to cause them to collide with a large stationary object such as a wall or the ground). Midnight Express' main stunt with his kinetic control, however, is a variant on the fastball special used by the X-Men. Express accelerates to full speed, then comes to a complete stop and transfers all of his momentum to a nearby target, usually to send an enemy very, very far away or to turn one of his more durable teammates, like Champion, into a high-speed guided missile (remember boys and girls, Midnight Express' power gives him control over the speed and direction of an object.)
And, while being an obvious fashion statement, Midnight Express' goggles also contain special lenses that afford him protection from rapid changes in light intensity and have light-intensifying and infra-red sensors that let him see in dark and near-dark lighting conditions. These lenses were standard issue for the Dark Force and M.E. never bothered to return them to Uncle Sam...
While being the coolest Cavalier obviously entails myriad talents, Midnight Express' skill with computers and electronics are a security person's nightmare (imagine a hacker who can react faster than the computer he's hacking into, a Cray may as well be a VIC 20.)