When the First Embrace was completed, the very existence of the two Blood race individuals became interconnected, inevitably affecting each other.
Furthermore, given that your Warrior was weaker than Melia Corando, despite being the initiator of the First Embrace, he ended up being influenced by his own Descendant. However, the extent of this influence was limited to dreaming about each other's lives.
You must understand, Murphy, that their presence in our world is merely a projection.
Their true selves have never been here, and the vast distance between the two worlds can only be measured by Divine Spirits. This distance is enough to leave 99% of the 'bad stuff' on our side, so one could say that this is the best 'protection' fate has granted your Warriors.
It wasn't a casual remark when I suggested he shouldn't return to Transylvania for at least seven days—it's the 'standard procedure' used by Vampires to deal with such situations.