So it is like this... the vitae is a fatal addiction. It seems that LikesBlondes is pretty faithful to the base background material so if that maintains, there are some issues and goodies.
It is a fatal addiction because in general the person taking the vitae will lose their humanity over time, not completely unlike vampires do. As they stop aging once they take the first drink, and are thralled (barring some perk that averts that or a discipline/power that affects the number of drinks necessary) after 3 drinks. This means that they are in love with the blood. Some folks generalize it to the vampire, Laurie recognizes that it is different from the love she had for the MC as best friend and maybe more. It is an addiction to the blood.
Now the more blood you drink, the more powerful you become as a thrall. Sharon's philosophy as well as Andrew's means that Andrew is basically starved for most of the month, but retains a bit more free will. Free will is very important if you care about the thrall, and not so much if you do not. The vitae can power disciplines for the thrall, the first they get are the physical ones, particularly enhanced strength/potence. Laurie, and eventually Mirri and Carmen will have the possibilities to learn some of what the MC can do if he feeds them more and teaches them-if we follow the source material. Of course in the source material, you wanted your thrall to have full blood so they could fight well on your behalf during the daytime. Sharon's way basically ensures that Andrew is not aging, and is thralled, but not much else.
So it is a double edged sword. The fatal part is the death of free will, loss of humanity, and an absolute need to keep vitae in their blood stream lest they age. For Laurie this is not an issue, and won't be for a long time. For Andrew, he would start aging again, somewhat accelerated rate, until he got more vamp blood.
Other topic
as of a couple minutes ago, no update on Patreon yet.
peace