Fire brigades are not an uncommon thing to have in a large city. It's going to be an effective city-state called Terkat, originally a port city of Dugong that served as the trading post for the salt mined in Selville (so it's pretty much directly north of Selville, on that bit of bay, and is considered by most to be Selville's "shadow"), but as it grew into its own thing it effectively became a city-state, with the merchants and such who traded there needing to fund their own law and mercenary enforcement. It's a city full of rags-to-riches stories, and rife with ruin. What happens in Terkat, stays in Terkat. It's one of the wretched hives of scum and villainy in this world, and while it's not the largest trading port in the South or even in Dugong (Quindol is the capitol for a reason), it's where you go to get your seediest of information, where you go for your black and underground markets, and where you go if nowhere else wants or will take you. All kinds of races mingle in Terkat, which is a cultural melting pot of outcasts from all over, and a sanctuary of half-breeds--it's a place where few are likely to judge you by your looks or race (except perhaps to note your special abilities, because nobody trusts easily in Terkat, too). If you ever come across a half-breed who is typically considered undesirable, but is comfortable with who they are, they probably grew up in Terkat somewhere. Terkat is a city of high contrast, where the rich are exhorbitantly rich, and the poor are truly destitute. The main drags of the town are beautiful, ornate, and impeccably clean, and that's where the tourists tend to stick. Those that venture a street or two beyond will find themselves in the considerable slums of Terkat, rife with pickpockets and worse. Law and order in Terkat is technically Dugong law, but with private funding keeping the police/peace guard in business more than tax money. The police there know better than to go over the local customs and guilds--there's a sort of balance there, and the power is balanced between three of the wealthiest groups, who all have their own territories.
Public services like the Fire Brigade are well funded because of how tightly the city is packed--if a fire should break out, quite a bit would go down in flames without an organized task force to handle it. I imagine there are multiple Tieflings and other fire-resistant creatures in the brigade and probably at least one water elemental of some sort. There are at least two squads, so one is always on duty, and each is made up of full-time brigadiers and the part-timers who are on call. The full-time brigadiers live in the firehouse dormitories and the chief gets an apartment in the firehouse to herself. The firehouse is on the outskirts of the main drag, on the side closest to the water for ease of taking up water, since they have to cart their water to the fires (no pipes or hydrants). Terkat would, however, have a sewer system in place.
IC Background: Yvada Jacobsen is the child of a willing union between a demon and a Drow elf demon summoner, who probably summoned her sire. Owing perhaps to her impressive horns (for a Tiefling, anyway), her mother died in childbirth and her demon father brought her to his Tiefling half-brother, Yvada's uncle Corvin Jacobsen, in Terkat to be raised and has otherwise had only a passing or mild interest in his daughter; he seldom visits either of them even now. She does not know if she has any Drow half-siblings, as her father has not been helpful in that regard (he honestly never knew and she suspects he never cared enough to find out, considering it was probably not a long-lived relationship), and as such her uncle Corvin and his wife have been the only people she's considered family. She grew up in Terkat in her uncle's shop, Jacobsen's Rare Books & Printing Press, although it was originally just Jacobsen's Printing Press and did not officially change its name until she was already in training to join the Terkat City Fire Brigade. The shop is a street over from the main drags of Terkat, on the edge of the slums, but still in a reasonably respectable neighborhood. As a child there had been a fire in the same building as her uncle's shop (though it stopped two shops over), and the anxiety of her friends and her family's livelihood going up in flames which otherwise could not hurt her or her uncle left an indelible mark on young Yvada, as well as seeing another Tiefling putting his fire resistance to good use as a member of the Fire Brigade that responded to that call.
Yvada has never felt pushed or driven to refute the dark stereotype Tieflings must put up with elsewhere due to her upbringing in the mixed city of Terkat (and close enough to the slums that many of her playmates and friends were also of outcast or "undesirable" races), and she is as unlikely to trip all over herself trying to be helpful or "good" as she is to try and swindle or deceive. The closest she might have to a push towards being traditionally good would be her dislike of her definitely evil demon father, who apparently would have preferred a son. However, she does have compassion for the poor and the inhabitants of the slums, having grown up alongside several of them and having gained a certain amount of empathy with them. Two of her childhood friends from the slum also work with her on the Fire Brigade. Her desire to join the brigade came both from the impression made by that fire she witnessed first-hand as a child and her love of order, perhaps the byproduct of growing up in her uncle's library (which is what eventually expanded into the bookshop portion of his shop). Those that know her suspect that, had she not been interested in the Fire Brigade, she might have considered being a librarian or going into law. Between her bookish uncle and his sorcerer wife, she grew up with a great love of stories and learning, and enjoys quiet evenings spent in front of a warm fire with a book and a cup of hot cider or warm mead, and perhaps a cinnamon bun (her favorite sweet, but she honestly likes any cinnamon-packed sweet). Her sweet tooth is well known amongst her friends and family, but not as well known (or joked about) as her complete intolerance of spicy food (she can't handle any at all). She's also known to be fond of strategy games, such as chess, and is considered quite good at them (although not on the level of a grand master, it's just a hobby for her). Another hobby of Yvada's is knitting, partially because she dislikes being cold (in spite of her Tiefling temperature resistance), but also because she appreciates the mathematical nature of the technical aspect of knitted construction. (Her favorite thing to knit, however, is stuffed toys, which she often gifts to children who are affected by the fires. She has a soft spot for children, and particularly orphaned ones.)
She sports four horns, the top two of which curve up and backwards, with the lower two curling at the sides of her head. The horns are a dark grey with lighter grey striping and ridges. Her hair, owing to her Drow heritage, is snow-white (even the hair tuft at the end of her thick tail), a contrast to her shadowy purple-grey skin. Her skin is not nearly as dark as a Drow's, and her freckles are lilac to white in color. Her eyes are a solid red, so it is not particularly easy to guess what she is looking at unless you've watched her eyes move. Aside from the tail and horns, her body is humanoid in shape, with clawed fingers and toes. The distinctiveness of her appearance means she's an easily recognizable figure in the city, although not particularly influential, and certainly not as well-known as the city's wealthier inhabitants; it wasn't always a good thing, and sometimes it's still not a good thing to be so unusual, even in the city of the unusual. Yvada's upper right horn tip was snapped off in a scuffle when she was a teenager when snatchers attempted to kidnap her to sell as a slave for her exotic and stunning appearance--she has been wary of slave traders ever since, even though none would be so foolish as to attempt to kidnap and sell an official now.
Her personality is fairly cool and professional, although she is fierce if she believes her family, friends, or comrades are being threatened. While Yvada is not shy to bark orders and take command in her line of work, she is otherwise somewhat introverted. She's normally logical and has little problem admitting that she does not know something or is wrong (once she believe she actually is), but can become very bull-headed in an argument, especially with an aggressive or pushy opponent, or if she suspects someone is trying to pull one over on her. Yvada's chief concerns seem to be maintaining order in her fire station (she is compulsively neat and orderly--the Fire Brigade's files and paperwork have never been so organized in the history of the city since she became Fire Chief) and keeping any fires that spark up from getting very far or damaging very much. That's a bit of a struggle during the dry summer months on the salt flats of Dugong where the scorching daytime temperatures dry things out and the dropping nighttime temperatures mean makeshift fires made by the homeless to help keep warm. However, her meticulous planning and trained routines with the Fire Brigade have made her one of the most effective Fire Chiefs in the (not terribly long) history of the city. Yvada's apartment at the station is fairly minimally decorated and always impeccably neat and organized--many of the boxes and drawers even sport labels. Accurate ones. Her style of dress is likewise modestly minimal, with mostly solid colors (in often bright hues) and not a lot of large or irregular patterns, but she enjoys wearing intricate or ornate accessories (such as multi-colored scarves, bangles, and hair beads). Her favorite color is a bright red-orange.
While not confirmed, there is a rumor that she may be romantically involved with the Dragonborn baker at her favorite bakery. This could, however, simply be a side-effect of frequent visits to satisfy her sweet tooth, but the baker himself is surely sweet on her.