Mechalis would be a Rocket Camel Vendor. She would fly to different major cities (perhaps one city per week), exploding on the scene and causing mayhem and uproar and attracting lots of publicity, and hopefully making a nice tidy profit once the smoke clears. She’d have to take one week off every now and then to replenish her supplies, but for the most part, she’d be devoted to sharing Rocket Camels with the world.
Thermalix would be a secret Quest Giver whom players would normally find lost in a corner somewhere in Dalaran. If you talk to her often enough, you’ll get a quest where you can offer to escort her safely to the Auction House. On the way, you will be assaulted by visions of nightmarishly expensive armor and Minigob Manabonk. If you defeat them all and succeed in showing her the way, you’ll receive some of the engineering crap she’s stored in her bank. If you’re lucky, you might even get an Explosive Sheep!
Centina would be a Transmog Specialist. She’d stand next to the transmog guy in Orgrimmar and critique your outfit loudly and in public. By critique, she means “inform you that your wardrobe choices need work, and your sense of color is totally … interesting,” and if asked, she’d recommend pieces for you. This means no one will ever talk to her.
Bombelina would be an optional, rare spawn that shows up occasionally in some dungeon you run way too often to care about. She would drop a prototype of her latest leather jacket design, made for those moments when you accidentally jump off your flying mount. They explode upon impact, thereby negating the crushing force of the landing!
Thingie would be a daily Quest Giver related to your profession. She would first ask you to produce 5 of something, which seems reasonable. The next time you do the quest, she’d ask for 50. After that, she’ll ask for 500 of the same item. She would continue this until you are so horribly bored you think the skill up/bag of shiny things isn’t worth it anymore, so you abandon the questline and quit. Months later, you’ll read a post on a site somewhere, saying that if you manage to survive all her requests, you get an epically shiny, super-duper rare mount. But she won’t let you continue once you’ve abandoned the quests!
Majig, who hasn’t shown up in the blog in her own right yet, would be that Quest Giver who keeps on walking away from you while you’re trying to read the text, causing the box to close. It isn’t a glamorous job, but somebody’s gotta do it.