"Noticed these, huh?" Brennan raised his brow. "The idea is Thayan, but the design and function is propriatory. You see, although we have access to magic, we're not the same. Your power is mostly innate, while mine is aquired. That means that when you cast, you draw upon inner reserves of magic, while I will to change it's flow around me. It makes it more difficult to access spell, I can't just accidentally spit them around, but it also gives me a wider arsenal of them. This also means, that when you miscast, something explodes or burns, when I miscast, consequnces can be... severe. These tattoos... well, they can't prevent miscasting, but they lower the likelihood of them."

Brennan walked over to one of the cabinets and began putting different items on the counter.

"Let's see... I have these Eyes of Charming, for one. Then there's Perfume of Bewitching, but that's mostly for noble ladies trying to score a husband... and that's about it. You must understand, the magic that helps to bend the will of others is not looked kindly upon. And so I can only sell so much. There's also Stone of Good Luck (Luckstone), it will slightly help with everything you try... "

"How much would you charge for the stone?"

 "The stone? Hm... 40 gold," Wizard answers, weighing the stone in his hand.

Oblivious to this Violet will still take out here book and starts  sifting through ist pages murmuring "Negotiation … the art of finding solutions to benefit both parties … or more confrontational using desires and fear … no that won't do."

She turns towards Brennan "That is a generous offer. How about you sweeten the deal. As we are about to help you, it would be in your own interest if we succeed." Violet tries to look confident yet charmng. "I pay you the 40 gold now and if we solve your problem you repay me say 25% of the price? Does that sound fair?"

 "Okay," Brennan slightly squints his eyes. "I can work with that."

I'm gonna leave it to you to add luckstone to the inventory and subtract required gold ;)

Crassus is going to whisper to Violet. "Could you lend me 100 gold? There's a salesman outside selling a greatsword that I think would be very useful in a fight, I'd purchase it myself, but I don't seem to have the funds. Also, there's a chance that you might be able to negotiate for a better deal, since you seem to be good at talking to people."

Violet is beaming with joy as finally someone reacted in an intended way. "Of course I can give you the money. Let me try what I can do? If you could excuse us for second."

She sifts through her book for inspiration on the task. Then suddenly she links her arms with Crassus like a fresh couple and strolls past the merchant stand. The familiar voice inside Crassus head is giving him instructions "Show her the way, then when you reach the weapons stand linger for a moment, whisper to her and point at the sword. Make sure the merchant sees you. Afterwards go to a nearby stand in earsight but out of earshot." 

After their little show she unlocks her arm heads back towards the merchant and addresses him with an enamored look on her face "Hello there fine gentleman. Might I ask how much you charge for that sword over there?" Violet points at the same swords Crassus did before. When she hears it's 100 GP her expression shortly drops to visible disappointment. She waits couple of seconds then retries "Oh no, that's more than I have. Can't you cut me a better deal? Look at that mighty warrior over there." She points towards Crassus. "Look at that beautiful physique, they way his muscles are toned and the firm grip of his arms as he holds you. And that''s just his appearance, let me tell you." Violet is romanticing about the Dragonborn. "You see for some reason my fiance has taken a liking for that sword and I want to gift it to him for our betrothal. I know you run a business here, but you don't want to stand in the way of love do you?" She looks at him pleadingly. She rummages inside her bag "I could summon up something in the vicinity of 70 GP. We could also give you an invitation to our wedding or name our firstborn after you, please."

"This is all lovely, lass," the merchant answers. "But the problem is, this kind of blade is hard to come by and even harder to make. I can't just give it at self-value. The enchantments poured in it, do you have any idea how much magi charge for that? Sorry, but 95 gold is my final offer."

"Well if you can just wait a little bit." Violet heads over to Crassus. They start to argue a little bit. Then Crassus hands her a pouch. Violet returns to the merchant and hands over 95 GP. "Here you go. I guess romance is dead."

When Violet walks back from the salesman, Crassus is going to thank her for buying the sword and attune to it. "Thanks, I owe you one."

You seemed to be finished here. You're not leaving the location unless everyone is done, but let me sum things up just in case:

Brennan (the necromancer) has sent you investigate increased guards attention towards him and, supposedly, his colleagues. Said attention comes mostly from lieutenant Jarvey, a young noble working under Captain Lue, and ambitious and cunning man, a brilliant tactician with whom Crassus has already crossed paths. That did not go well, as Crassus may choose to reveal to his companions. Which you agreed to do. In exchange, he will help with the curse plaguing the fey tree. Plus, he can become an ally in the matters that concern the arcane, being a powerful wizard and all.

So the option that I see (remember, you are not limited to them, it's just a layout, there might be something I missed, or omitted):

1. Talk to the other magi about the matter, see if they have any clues. Brennan could point you to them, as it is in his interests.

2. Talk to lt. Jarvey (that will require finding him, but I believe Madame Velour can help with that, if convinved).

3. Talk to the Captain Lue (should be in guards quarters in the port). Remember, however, that you're in the city not strictly by the book and captains reach (and wit) is greater than that of his lieutenant, so your ability to remain within Nyits borders will depend only on your own power of persuasion. He will recognize dragonborn if he's not hidden.

4. Forgo talking and discover other means of obtaining information. Again, Madame Veloure is your best friend in this matter, but just like before, she will not simply help because you ask. Convince, lie, promise. I don't suggest trying to scare.

Since Crassus knows about the Captain, he might as well let his party know about him as well. "The Captain is a cunning bastard that I knew from my mercenary days. He knew how to come up with a plan for battle and see it carried out. I can't imagine what he'd be doing working in this city, I don't really imagine that overseeing noble brats on the city watch was something that was part of his grand ambition. Fighting him wouldn't be a good idea. The war might've been a long time ago, but he's not the sort of man to let himself go. I also don't think that it would be a good idea for me to be around if we saw him. The two of us didn't leave on the best of terms and I'm a pretty recognizable guy."

"Now you are telling this, Crassus. Great." Violet heads back to Brennan. "OK, things came up indicating that deception might be needed. So how much do you charge for the hat?"

Crassus is going to stop Violet for a second before she heads off to Brennan. "Well if you're planning on speaking to the Captain, then all of us are going to need those disguise hats, since one might be able to say that we illegally entered the city and the Captain would definitely be the type to figure that out. Maybe we should speak to the mages or someone else first and speak to the Captain if everything else fails."

"You mean the Hat of Disguise? I only have one at hand. They're not difficult to enchant, but the preparation takes time. I can have more in... 2 days. This sort of trinket sells quickly in Nyit. And since you're using it for my errand, I suppose I should give you a discount. 20 Gold."

Brennan scratches his arm and continues.

"Oh, and by the way... This hat uses the same spell as the Green Hag of Witchwood. It will not hold up to touch, so if you plan to disguise your scaly friend, perhaps don't overdo it, change his shade and facial features and leave it at that." Then, turning to Crassus, "How do you feel about purple?"

"There's worse colors."

"Yeah, could you prepare some more. Maybe we look elsewhere first."

"So do you take this hat or not?".

"Yes, I take the hat, so you have some advance payment."