Select strains of elder vampire bites have been documented giving euphoric effects. This is thought to have developed as a way to cultivate docile and eager thralls.
When these vampires first bite a victim (most effective at the neck), the subject feels intense shocks of pain. This will immobilize the victim. This stage is important- if the effects of the bite onset immediately you would find the subject attempting to stumble away in a half drugged state.
Once the vampire has a consistent stream of blood (20-30sec) their teeth with start involuntarily injecting the substance intravenously. This produces a rapid and powerful high for the victim.
Subjects describe a warm, tingling sensation spreading from their neck to the rest of their body, waves of pleasure that match in tune with their aggressors gulping. At this stage many will get disoriented, briefly forgetting where they are and even who they are. You can see subjects gripping involuntarily onto the aggressing vampire in an attempt to relieve the intensity.
Experienced vampires steady the subject at this stage, as many are prone to falling over from disorientation. After (40-60sec) physical touch will be enhanced so that the brush of fingers on skin or lips suckling their neck will be sexually simulating, more sensitive subjects can experience multiple orgasms from the sucking motion alone.
In the last stage the victim will then enter a weak stage of chemical hypnosis. This temporarily rewires the victim to obsess over the vampires attention: giving them incredible bursts of pleasure when the vampire looks at touches them. This gives the vampire time to properly administer hypnosis, trapping the victim with them as their thrawl.
Overtime, thralls begin to associate the pain with pleasure. Chemical hypnosis builds up and settles as their default state, as well as physical dependence on the bites effects. This leaves the master vampire with willing and eager cattle to feed on.