Caleb is a Terran astrophysicist and one of the Sol system's leading experts on warp currents and their influence on starship traffic. He likes other people well enough but tends to enjoy his solitude- when he's planetside on Terra he tends to keep nocturnal hours, and when he's up in space he feels most at ease, secure in his deep space research stations. While Caleb will give new people the benefit of the doubt, he isn't a very welcoming person until he comes to know you better, and if you earn his trust you, well, you still won't ever get a warm greeting from him, but you'll know he respects you when you share a space with him. The vibe is different. He's like that. He's a big fella, and he finds Callistan fashion tends to fit him better than Terran cuts, so he'll often be seen wearing slatted Callistan shirts despite his apparent lack of quills.
Warp currents: just what are they, exactly? Well! Beneath the fabric of traversable space, between habitable reality and subspace, there is a membrane of astroplasm keeping our universe intact. We're only beginning to learn about what astroplasm is made of or where it comes from, but in the past hundred years we have learned how to harness it to make space travel easier. It's known that astroplasm has fluid dynamics to it, and that it's constantly in motion, and like Terra's own seas it flows in currents- warp engineers have learned how to deploy technologies that can reach towards the boundaries of physical reality and harness these currents, riding them like sailing ships of old. You can go anywhere in space, but if you want to get somewhere quickly you'll need to follow the warp currents. You can't travel faster than light, but with a proper warp sail and a skilled engineer you can come close to it.
Since warp currents are fluid and often change, scientists like Caleb study them and document these changes for broader use. Caleb spends a lot of time in deep space laboratories- tin boxes set in space near satellite outposts- where he manages probes and monitors the flow of warp currents. Starship charts need to be updated frequently in order to be of any use to starfarers, and Caleb is in charge of supplying the raw data those charts need to remain useful. He understands the flow of warp currents, particularly in the effect the rotation of the planets have on them and the way in which those currents weave between those orbits; understanding these tendencies helps predict how warp currents will change ahead of time and provide helpful context for commercial space travel to connect between the many worlds of Sol. Transporting goods and people between moons and planets quickly is important, and it's folks like Caleb who help make that possible. They're the unsung heroes of the space age.
Caleb is an old friend of Red Raven's Lydia, the two studying warp theory together at the Academy of Astrophysics in Athens. He was quiet and reserved, even back then, and found comfort in Lydia's unobtrusive shyness, and so the two helped each other in their studies, becoming experts in their fields. Lydia went on to develop warp engines for Delta Astronautics, while Caleb pursued astrometeorology with the Terran Star Navy. The two kept in touch over the years, and Caleb would help Lydia test her Pocket Drive technology, reporting its movement through space off the books using the warp current research facilities he was stationed at. He's not a very outward and mirthful friend, but over the years- as she found herself leaving Delta and becoming Red Raven's warp engineer- he's always kept an open door for her. Whenever she has questions or she needs a favor, Caleb's willing to lend a hand. He's a leading authority in warp theory, he can bend Star Naval regulations here and there since he's too valuable to fire and replace. The Sol system's trade routes and transit systems depend on Caleb's work to stay up to date and expedient, so if he misappropriates his space station or causes a problem here or there to help an old friend, what are his bosses gonna do? Fly out to the middle of nowhere and scold him? A disciplinary phone call is just a blip in his schedule, and once it's over he's back to enjoying the quiet isolation of life in deep space, with naught but the hum and ping of his scientific equipment to disturb the silence.