If they're going for the thief archetype, then it should be Ravnos.
Due to their inherent clan weakness, the Ravnos clan are all criminals; each Ravnos has a specific vice ranging from plagiarism to mass murder. When the opportunity to indulge that vice is present, Ravnos must succeed in a self-control check to avoid indulging it.
Should, but won't, because they're too mindful of walking on eggshells. So it'll probably translate into being stealthy, hence Nosferatu.
Nos and Malk for paid DLC.
Except they went on record saying that all and any clans they release in the future, post-launch, will be free DLC.
But since you slapped me with the fake news post rating, here's an official source on that claim:
https://www.pcgamer.com/vampire-the-masquerade-bloodlines-2-preview/
"The one thing we can say, we will have a good amount of clans in the main game that are really interesting, but we'll support it with more clans after launch," said Christian Schlütter, lead producer at Paradox. "And one thing that you need to write down is that every clan that we release later on will be free. We will never charge you for any clan." I wrote that down.