Hirudo Score ❖

Hirudo score is a term first used by Divine Solis fleshcrafters, although it now sees wide enough use to no longer carry a direct association. In simplest terms, a vessel's hirudo score is a measure of how readily their body will metabolise ferrous humor from foreign sources. Hirudo scores exist on a scale from one to ten, with one denoting "rejection with prompt expulsion" and ten denoting "immediate subsummation into vital systems."

While a high hirudo score allows a vessel to forego traditional means of nourishment in favour of consuming ferrous humor, it's exceptionally rare for a vessel with a hirudo score of six or above to be capable of comfortably consuming anything else in the first place, owing to the telltale internal atrophy of longterm vesselry.

There exist very few vessels with a hirudo score above seven, at which point cascading failures of the vital systems tend to claim their lives. It is also worth noting that a hirudo score does not correlate with a psychological tolerance for the consumption of ferrous humor, although it does tend to induce cravings and symptoms similar to barbiturate withdrawal in its absence.

To measure a vessel's hirudo score, a physician provides the patient with a sample of ferrous humor to imbibe. While physical reactions prove to be fair measures of lower scores (vomiting, wretching, and shivers), higher scores require a blood sample to be taken and analysed, determining exactly how much ferrous humor was subsumed and at what rate.

Because the differentiation of early scores tends to be inconsequential, levels one through four are often grouped together to save the bloodwork.

Questions and Answers ❖

Q: Since blood and ferrous humor are interchangeable, could a vessel sustain themself entirely on period blood?

A: Only above a hirudo score of 6... but yes.


Q: Can hirudo scores change? Will it get higher as someone spends more time as a vessel?

A: Hirudo scores naturally increase over time, but they tend to plateau as long as the vessel isn't deliberately trying to erode the neural wall between themself and their pygmalion (overbursting, for example, runs the risk of making a hirudo score surge). Hirudo scores are not known to decrease, and a sudden increase in hirudo score often kills the vessel within a few days as their body struggles to adapt to it. Even going up one full level in a year is an incredible amount of physiological strain on the human form.

While nothing about it could be studied and even the most basic details of it are apocryphal at best, descriptions of the semi-mythological Kishar disease, Eliczan’s Syndrome, resemble those seen in vessels experiencing shock from a rapid surge in hirudo score — albeit the commonality in those stories is the symptoms presenting in new births, which hasn't been recorded even once since.


Q: What's the connection between hirudo score and one's potential ability/compatibility as a vessel?

A: This is one of those questions I've gotta be careful answering because it's really easy to get the wrong impression here. The short answer is that it's intimately correlated, but correlation does not equal causation.

Having a high hirudo score is actually a bad thing, but also an inevitable thing. Your life gets worse in material ways, even though the score itself technically only exists to measure a benign physiological anomaly of vessels. You can think of it kind of like leukocytosis: there's nothing actually bad about the elevated white blood cell count itself, but it shows that the body is under great stress and is doing its best to adapt to its condition.

A hirudo score measures a symptom of attunement, which is a vessel's nature shifting away from humanity as they spend time bound to a pygmalion. There is no way to measure attunement because it's not actually quantifiable, but hirudo score seeks to measure one symptom of attunement because it provides relevant parties with a good idea of how quickly a vessel is changing, along with just how intense the changes are.

Old vessels always have high hirudo scores, so it's easy to notice this and assume it's a measure of power. More accurately, anyone who can survive a hirudo score above six for longer than a few days must have already been exceptionally suited to surviving the conditions of attunement. All hirudo score measures is a vessel's ability to take in foreign ferrous humor, but because this is a symptom of progressing attunement, it can also be used to get a good idea of a lot of other things.

It's not a hard rule, but about half of vessels that exhibit stigmata first begin to manifest them after passing hirudo score three. Only 5% of vessels manifest stigmata before passing hirudo score three, and in those cases, it's usually a property of the pygmalion rather than one of the vessel in question. Additionally, if someone passes hirudo score eight without dying, it's a safe bet that they're going to reach ten one day if something else doesn't kill them. The reason for this is that the worst of vital system atrophy tends to occur at hirudo score seven. Kind of a golden years situation!

A high potential vessel can have a low hirudo score, but all that means is that they're wet behind the ears, so to speak. As long as they keep pushing their limits, they'll elevate it one day. Someone with a hirudo score of nine is never going to be a pushover, but that doesn't mean that they're necessarily better than someone with a hirudo score of five. A high hirudo score means a vessel's mettle was tested — and they survived.

The best a vessel can hope for is that the elevation takes place over a long period of time. A surge in hirudo score shows that something has gone horribly wrong with your body and you're probably going to die from it. The hirudo score doesn't cause this, nor the violent eruption of stigmata and cascading failure of vital systems that shortly follows, but it's connected... so the slightly less short answer: a hirudo score is a bad measurement for anything beyond a vessel's physical health, but it can give you an idea of what exactly you're going against.

Just as a final note, everyone is born with a hirudo score of zero. there have been no recorded births where a human was capable of subsuming ferrous humor naturally, as that would require being bound to a pygmalion before birth. A parent being bound to a pygmalion doesn't cause this, and even if it did, nearly every vessel is rendered infertile in the first place.

It's not the kind of thing your body likes to produce children after, if you catch my meaning.