There's another way to do the Undying Vampire, which is more basic to the rules of Cypher System. My table came up with this idea:
1. Take the vampire racial descriptor for Alternate Origins (a supplement for The Strange which works equally well with Cypher System)
2. Use that descriptor, then apply two additional modifiers:
Corrupting Touch - any time the Undying makes flesh to flesh contact with another creature for any reason (including a bite) this initiates an Intellect attack against the target. The target if injured receives -1 Shift against charisma and influence based checks for 24 hours; these can be cumulative, and are addition to any other effects applied as a result of the skin to skin contact.
Inability – Memory Fugue: Most undying appear to have no realization of their nature, even as they commit their acts of destruction and murder. Very ancient Undying may become acutely aware of their condition and embrace it, while young and new undying seem to “black out” when they commit vampiric acts, and go into violent rages if confronted with hard evidence of their actions. This selective memory loss seems to be due to the inability of the fey ancestry to reconcile their necromantic transformation due to the loss of their immaterial afterlife in the feywild. All Undying suffer from this inability to reconcile their natures when it is demonstrated, and suffer -2 shift penalties to intellect defense tests when trying to remain in control or reconcile such evidence when confronted with it. Very ancient Undying may spend 3 XP to reduce this to a -1 penalty, and ancient undying may spend 10 XP to remove the penalty (but must be at least tier 5).
Additional Equipment: one relic weapon of up to expensive rarity and one relic item from your living years as an elf.
Initial Links to Starting Adventure:
1. you are an ancient undying recently awakened by your fellow PCs from some grave, and now wandering the land with a memory fugue, trying to remember who you are.
2. You were awoken by tomb robbers whom you killed, and you wandered off, met the PCs, and have been traveling with them while recovering your wits.
3. You were slain by orcs or other creatures in battle recently, but have no memory and are oblivious to your condition. Your PC companions assumed you simply had good luck to escape death.
4. You were killed by another undying elf and left as a husk who came back to life. You have one or more PC allies taking care of you who may or may not realize your condition.
By using the Vampire descriptor it covers the blood drinking and vampiric limits. The corrupting touch encapsulates the ability of the Undying to drain charisma, and the inability covers the distinct madness that corrupts the undying.
This looks like the way we will go.