Hey there, I'd like to join! I see there are a lot of posts though so I'll try to read them but if it's possible to have a catch-up summary that'd be really appreciated.
Canon Characters:
Autobots:
Cosmos
Decepticons:
Thundercracker
Neutrals:
Nightbird
OCs:
Decepticons:
Designation: Welkin
Frame-Type: Mech
Alt-Mode: Heavy-built experimental military aircraft.
Rank: Commanding Officer. Oversees the Air Warriors, and is often handed responsibility of the more unruly troops, such as the Insecticons, due to his infinite patience for such tasks.
Appearance: In bot mode, Welkin is an intimidatingly large mech, rivalling the triplechangers in size class. He has a sleek black paint job with verdigris biolights, classic red optics and dark grey face plates, with a jagged helm that makes his expression often seem crueller than he intends. His wings are upside-down on his back, which is necessary for transformation, though it aggravates him that his Earth alt-mode requires this. His cockpit is tucked over his chest and the glass is tinted grey so that is is impossible to see inside. Other than this, he is relatively kibble-free. In alt-mode, mass displacement allows him to carry a Cybertronian pilot in his cockpit and about three other passengers in the lower compartment. He has several powerful turbines lining his wings, and multiple laser turrets. He is built for efficiency rather than elegance, though he does manage a fair amount of agility despite his cumbersome build.
About: As his name suggests, Welkin is incredibly proud of his superiority over the air. He can often be found just flying for the sake of it, fuel crisis be slagged. He likes to discuss flight manoeuvres with the Seekers and admires all who take to the air with skill. He is very easy going with his fellow Decepticons and loyal to the cause, though his loyalty doesn't diminish respect for Autobots where it is duly earned, that said, he'll send anyone to the pit without a second thought if ordered to. He is also a devout worshipper of Unicron, though he's quite happy to merge alien religion with his own, often invoking human sky deities during battle. His friends include Dirge, Thundercracker, Skywarp, Astrotrain and Blastoff. He is on good terms with the other Decepticons. He doesn't have any particular Autobot he despises, but he's less lenient on those he perceives to be cowardly. He holds no contempt for neutrals, though won't go out of his way to help them.
Neutrals:
Designation: Coldash
Frame-Type: Femme
Alt-Mode: None, she's a monoformer.
Rank: N/A
Appearance: In bot mode, she has no kibble due to being unashamed of the fact that she has no alt mode, and seeing no reason to hide it. She has a slight build, being of an average size class and not a war frame, though this doesn't mean she can't hold her own. In fact, she uses her less threatening size class to her advantage, allowing others to underestimate her. Her paint job is mostly white, with ice blue forearms and calves and silver tilde decors on her chassis. She has grey biolights and blue optics and silver faceplates, with deep blue turquoise that lead down from under her optics to the bottom of her faceplates.
About: Coldash is too much of a people-pleaser to pick a side in anything, including the greatest war to ever tear her planet apart. Believing that the ideals of the two factions should be reconciled, she firmly sat for four million year on the proverbial fence, and does not intend to come off it any time soon. When she came to Earth, she immediately decided she liked its local lifeforms, including humans, and strives to help keep them safe when Cybertronian activity threatens them. She'll help those in need, and use her medical skills to fix anyone she finds left behind in any of the skirmishes, but if they ask her to join them, the request falls on deaf audials. She has picked up a number of handy skills to compensate for her poor fighting ability which have helped her survive this long. Her friends are Nightbird and Macha, she is on good terms with most other Autobots, Decepticons and Neutrals. She has no quarrel with anyone in particular.
Name: Macha Herrieu
Gender: Female
Occupation: Hermit
Appearance:

(Google betrayed me to find a less 'perfect model' looking woman, but hey, you get the idea what she looks like).
About: Having been passed around institutional care and foster homes all her life, she had no issue isolating herself in the mountains as soon as she was of legal age to care for herself. Macha is unsure of her heritage due to being an orphan, but she certainly has Native American roots since she has the characteristic dark, straight hair, dark eyes and set features. Despite her attempts to live life relatively cut off, she finds herself caught up in Coldash's attempts to minimise casualties and help Cybertronians on both sides. She is not a particularly skilled fighter but she is quick with her hands and her wits and multilingual to boot. Her friends are Nightbird and Coldash. She is wary of all Cybertronians and humans alike, but willing to be reasonably amiable they don't snoop around her home, or try to mine her mountain for energon.