Background: Before the war, Jetfire was a scientist at the Academy. However he and Starscream met there, they became friends - as close as siblings - and research partners, which caused him to take a long time in joining up with the Autobots. This suspicion was what caused Prowl not to either reveal to Jetfire he was checking out the new Decepticon mobile battle station with a group of Autobots, or, indeed, even bring Jetfire on that mission, even as Jetfire had been the one to submit the original report on it. Jetfire questioned the escalating conflicts between the various splintered factions (the Autobots and Decepticons had splintered in smaller factions earlier when Megatron and Optimus Prime disappeared in a transwarp accident), noting that there was some sort of pattern to these things, and that he just couldn't see it. This led him to contacting Shockwave, as they were both similarly scientifically-minded and could, as logic dictated, set their differences apart and pool their resources to attempt to find this pattern.
When Jetfire went to meet with Shockwave to correlate their data and attempt to find out what was going on, they were attacked by Bludgeon, Mindwipe and Bugly, who shot Shockwave down and got Jetfire under control with Mindwipe's hypnotic optics. As they moved Jetfire to a vehicle, there was a remark that they'd misjudged Grimlock (they had sent the recording of Shockwave and Jetfire deciding to meet to the HQ of the faction Grimlock was leading), who chose that moment to attack. Easily knocking the "Chaos Trinity" on their afts and then immediately attacking Jetfire to "execute him for treason", Jetfire was loath to attack the dynobot in return, but didn't have to do that, as the Fallen showed up, easily rendering both of them unconcious.
Jetfire woke up with himself, Grimlock, Blitzwing and Hot Spot strapped to some sort of device which was channeling energy from their spark cores to open the Seal of Primus at the Well of All Sparks. The Fallen called them the Angles of Dissolution, casualties in a "war of the gods". Jetfire was having trouble to accept all this, but had Grimlock leave with the other two, and stayed himself to attempt to stop what was going on. With the help of Bumblebee back at the Autobot base, who brought up a containment field at Jetfire's coordinates, the energy wearing away at the seal stopped... But technically it was too late, but what came out of the seal, contained within the containment field, attacked the Fallen and then withdrew, leaving Jetfire alone. The Autobots and Decepticons then sealed the Well of All Sparks up, with Jetfire claiming he'd been blinded and seen nothing.
Later (much, much later), when the Nemesis and Ark had left Cybertron and disappeared, Jetfire was in a mission to find Prime/the Ark and hunt Decepticons in space, which later broke up into two teams. Jetfire and Omega Supreme thought it was more important to find Prime, while the others wanted to concentrate on hunting Decepticons. A time after they broke up, their ship registered an energy signature Jetfire first thought was the Ark, but as they finally came close to the planet, the signature turned out to be more Decepticon-like. Then the ship was attacked from the outside, and since Omega wasn't out of suspended animation yet, Jetfire had to handle the attacked himself, tricking it to follow the escape capsule, which disabled the strange mech (with a similar Decepticon-like signature as the one that had come from the planet) with an EMP pulse. When on the way to find Omega and dragging the escape capsule with the mech in it behind him, Jetfire was surprised by an avalanche and buried... For a few million/hundred thousand years, until the Autobots and Decepticons picked up the Autobot signal from the escape capsule (as the planet Jetfire and Omega had arrived at was Earth), and presumably, either then or later, Starscream found a still-frozen Jetfire and put him on the Nemesis for when he might be needed...
Which was when Starscream was attacked by his clone, Sunstorm. Jetfire fought the clone after Starscream defrosted him, using both afterburners and the revolving guns mounted on his helmet, unaffected (at least temporarily) by Sunstorm's radioactive powers due to his upgraded armour which was made to stand interstellar travels. Even after shooting the orange and white Seeker so as he should have died, the wounds were quickly closing, so Jetfire told Starscream to come with him if he wanted to survive. They then went to the Autobots, figuring out Sunstorm was a clone and also how to counterfeit Starscream's energy signature, so as to be able to lure Sunstorm away so he could be contained. The first attempt, with Bumblebee in a small attack ship failed when Sunstorm caused the ship to crash, but Jetfire went after the Seeker clone and fought him until Bumblebee managed to shoot the inhibitor they'd constructed onto Sunstorm. Sunstorm fled, and Jetfire's radiation-resistant armour was pretty much finished after that fight from taking abuse from Sunstorms powers, however. Jetfire called in their last 'ace' to fetch the now-contained Sunstorm; Omega Supreme. When Jetfire and the three minibots (Bumblebee, Cliffjumper and Brawn) came back to the Orion, they found the whole Autobot crew disabled, Starscream having sabotaged the engines so he could flee.
When Jetfire, Bumblebee and Cliffjumper found Omega again, due to interference from Starscream, Sunstorm had been rid of the inhibitor and defeated the giant mech, but he just needed time to recuperate. Jetfire made ready to leave in chase of Starscream, but Bumblebee demanded he'd come with and Jetfire bowed to that. They found Starscream and Sunstorm in the ocean, Sunstorm holding away a wall of water to reveal a Cybertronian seal on the seafloor, which, despite Bumblebee's interference by shooting at the Seekers with some of Jetfire's guns, Starscream managed to open. Having no other recourse, they followed Starscream and Sunstorm down into the cavern beneath the seal, Starscream attacking on their way down/in. Bumblebee threw himself out of Jetfire's cockpit to give them more ability to fight, and Jetfire transformed back into robot mode and attacked Starscream like that, driving him into the bottom of the cavern.
Jetfire was momentarily thrown by Bumblebee's disappearance, but Sunstorm had him, holding him by his helm. Starscream chose this moment to attack, shooting Sunstorm with a null ray he'd modified to turn Sunstorm's regenerative powers against himself. He then also shot Jetfire with another (normal) null ray shot, leaving him briefly alone with Bumblebee before Sunstorm got up again, was shot down, and then kicked into the pit of energy that was at the bottom of the cave. Starscream didn't have time to gloat for long, as Sunstorm returned, now even more unhinged than earlier, and attacked Starscream. Jetfire had woken up by now, and swept the Seeker out of the way as Sunstorm's regenerative powers, along with whatever energy had been in the pit started to destabilize him.
Jetfire said Starscream owed him and then flew off after Sunstorm, clearly expecting him to save Bumblebee, noting to himself that he'd failed to be as open-minded about the situation as he prided himself to be (accepting the possibility that Sunstorm might be supernatural), and that, despite that he and Starscream had been fighting for so long, that didn't really matter now Fighting Sunstorm in the skies over Earth, Jetfire noted the volatile reaction was getting worse, and decided to take Sunstorm as far up/away as they could get from the surface, to have him explode where he'd do no damage. Sunstorm then explodes, and, presumably, takes Jetfire with him (unpublish material point to that Sunstorm had been possessed by the Fallen, and at Sunstorm's death, the essence of the Fallen passed over to Jetfire, so he wouldn't have died).
Personality: Jetfire's a patient mech. He's not just slow to anger (and any expressions of such temper is usually subdued until further provocation, or if whatever provoked him was serious enough), but also has a high threshold for behaviour most wouldn't put up with. Things like verbal antagonism, teasing, physical cries for attention... Or even outright physically harmful, condesceding or otherwise "mean" behaviours, but there are conditions here; firstly, he tolerates more of this towards himself than towards others, and secondly; Starscream. His patience serves him well not just dealing with Starscream, but his preferred pursuits, which is several flavours of science. He'll go through his theories, hypotheses, facts and results as slowly as needed and if it takes time to get any of the results/observation, the time it takes is the time it takes. Jetfire doesn't do short-cuts when it comes to science.
Jetfire prefers a rational, logical take on things; anything that seems to be non-rational, supernatural, etc, shouldn't be taken as such... except if there's repeatable proof that no other conclusion can be taken. "The only basis for analysis is a repeatable phenomenon." This wasn't always so; earlier in life, Jetfire wouldn't have accepted even a shade of something not being based in natural laws and physical, observable reality. He was also an atheist. Due to certain events, however Jetfire has had to reevaluate this position, and has come to his current understanding of something being capable of being 'supernatural' if it can consistently portray as such. He's also become an agnostic instead of outright atheist.
He has a dry sense of humour, often using it (possibly partly seriously even) during rather serious situations. Jetfire is also not the most amazingly social person ever, and tends to speak in a rather dry fashion, often tripping into 'scientific asides' which tend to make him long-winded if he gets the chance. Not to say he can't tease those he's (somehow) become close to, it's just not something that'll come up with anybody, and he can be prone to answer jokes and such things very straight.
Jetfire prefers to work in consensus with others; he can (and will) take charge if it seems to be needed, but the situation needs to be rather spectacular for that to happen (or he feels responsible for it) to override his generally group-oriented leading or even outright more 'submissive' (as in accepting decisions and actions from someone making them) personality. He's loyal to those he considers friends (maybe too loyal for too long), even when said friend/s take decisions he doesn't personally agree with.
Jetfire is further not a warrior, soldier, and absolutely no murderer, but he can fight and does so competently and innovatively (using his afterburners, or the revolving guns mounted on his helmet) when needed. Overall, though, Jetfire is a scientist before he's a warrior, and would prefer to be able to dedicate himself to his scientific pursuits.
When it comes to Starscream (because Starscream totally needs his own section here), Jetfire both knows and accepts Starscream's less-than-moral behaviour, his attitude and his goals. To a certain degree. He doesn't agree with them, but that's beside the point; Jetfire liked and was loyal enough to Starscream he was torn when the Decepticons finally rose and Starscream joined them. He took long enough (and was probably flirtingly too closely with the Decepticon forces and Starscream) in joining the Autobots that they mistrusted him for the longest time. Jetfire and Starscream were, and are friends. Both were obviously upset at the "betrayal" as final faction lines were drawn, but, at least for Jetfire, this division, compared to their friendship, ends up not mattering in the end.
Still, he trusts Starscream (doing nothing when they approach the Autobots after Starscream has defrosted him to fight against Sunstorm and Starscream shoots at Bumblebee), but can also make Starscream *stop* and do something "selfless" when needed (with no more than a look as he doesn't actually ask Starscream verbally to rescue Bumblebee).
RP Sample, 3rd Person POV Prose: It had been surprisingly easy to - despite not knowing the circumstances or the situation - attack Sunstorm, simply knowing that Starscream needed some sort of assistance. Honestly, it had also given him something to focus on, especially when the orange and white Seeker didn't just defend himself, but displayed some... unnatural strength and that fascinating radiation ability.
"So, where, exactly, are you taking me?" Starscream didn't sound very impressed. In fact, there may have been a mocking tone underlying the sneer; he knew as well as Jetfire did that Jetfire didn't have a good grasp of the lay of the land, so to speak. And yet the Seeker was following diagonally above him, and not attempting to tear away.
"Where would it be best to go?" Jetfire hadn't really planned on forcing Starscream anywhere in particular, except get him out of the ship... Nemesis, before Sunstorm came back online. Waking up, clearly having been frozen just moments before the thawing-cycle had defrosted him, inside a ship he didn't recognize had been disorienting.
He was, obviously, playing into Starscream's hands by attacking Sunstorm, but he was hardly going to leave Starscream there.
"... Well. Uh. This way. The Autobots will surely render their assistance!" This came after a few moments of silent, slightly incredulous staring from Starscream, then the Seeker collected his words and then changed course. "Just let me do the talking, Jetfire!"
Jetfire vented quietly at that, but nodded in acquescience. He had no idea which of the Autobots were on the planet... Or that they'd even been on the planet at all.
What were they doing on this planet, anyway, both the Autobots and the Decepticons? Had the ship's scanner just not picked up the smaller Autobot signal for the huge Decepticon-like one masking it? It didn't matter. Putting those matters aside for the moment - as well as why Starscream had had his clearly still-frozen chassis on the Nemesis to start with, and for how long - Jetfire turned his thoughts back to the current situation, the one that he might actually be able to help rectify by doing what he could. What was Sunstorm, anyway? There must be a logical explanation to his displayed anomalies and deviances in the displayed tolerance for heightened radioactivity...
"Jetfire! Can you at least pretend to pay attention? We're coming in now... Ahh, the yellow runt, excellent. Just follow my lead, Jetfire," Starscream said, going from snapping to pleased in simply the time it took him to finish the sentence. And while Jetfire knew he wouldn't exactly approve of Starscream's method for approaching Bumblebee, Jetfire felt it best to, indeed, follow Starscream's lead for the moment.
He was reasonably sure Starscream wouldn't do anything to actually harm Bumblebee with Jetfire right there and Starscream in need of his aid. So when Starscream shot at the ground and forced Bumblebee to dive away, he simply kept his position in the air beside the Seeker, arms crossed, and waited.