She is apparently a citizen of Venore, employed by Theodore Loveless, a merchant and representative of Venore. Venore merchants invested a lot of money in Liberty Bay to make it a trading point. And Theodore is Venore's representative in Liberty Bay. Chantalle, like some other NPCs in Liberty Bay, are merchants from Venore.
Although the two praise Thais a lot. There are many rumors and documents throughout Tibia that documented the greed and cruelty of Venore's merchants. Some information can even be seen during Secret Service Quest (Different information in 3 quest options).
Some people think that Venore is like the little sister of Thais, it's a luxurious and attractive place, and that's the image they want to pass to the society. But Venore is a rotten and corrupt city. Venore's merchants sabotage and create rifts between the cities behind the scenes. Have you ever seen that city? Is full of undead NPCs (the main enemies of humanity in Tibia).