Dracula could have been the culmination of the connections Vanessa had formed with Dorian Gray and the Creature / Calliban / John Clare.
She had strong connections with both of them, based on their differences (and therefore their similarities) and their shared loneliness, which manifested physically (sexually with Dorian Gray, and a few kisses with The Creature).
But Dorian didn't truly know Vanessa, and his obvious danger allowed her to decide not to continue a dark relationship. Therefore, he was unable to get to know her more deeply.
With The Creature, it was a bit purer and brighter, but above all, they recognized themselves in the hardship of their circumstances, which they didn't particularly enjoy, hoping for an optimistic ending in the future so they could find their place in this world. A kind of yearning for normalcy. Or simply hope for a real end one day (so death).
Dracula, on the other hand, while aware of the somewhat tragic nature of his and Vanessa's circumstances, fully accepts them and wants her to accept herself as well and live with all that. It's not like the Creature. Or even Dorian Gray, because Dracula was able to get to know Vanessa from afar by observing her, and under an identity that would make it easier for her to connect and open up to him. But this allowed him to understand her completely, and that's what had drawn Vanessa to him : the understanding of all her facets and the total acceptance he offered. The possibility of not conforming to this world and finally accepting her difference. He sees both her light, and the darkness she hide in her, and accepts and understand everything. It encourages her to fully accept her difference rather than continuing to hope to be accepted in this cruel world one day while continuing to torture herself over her own nature that people reject. They are exceptional and they must fully accept it instead of aspiring to some form of normality or ultimate end.
In addition, Dracula combined the emotional and physical aspects in the same time. Whereas with Dorian Gray, it was mostly physical with a nascent emotional connection that Vanessa stopped, and with the Creature it was mostly emotional and not very physical (even if they shared kiss sometimes, but always chaste).
But the show decided to ruin everything !
(But I must say that I love all the ships, even if I prefer the relationship with obviously Dracula)
