For a dissenting opinion: boring, marginally pretentious book. Tries to bring up some interesting ideas, but loses the plot along the way. Also random Dracula in space. Couldn't get myself to finish it.
If you want a really shoehorned scifi vampire, there's a David Weber book in which it comes out of fucking nowhere towards the end.
This helped explained their downfall with man creating euclidean geometry everywhere and was taken advantage of when they where brought back as they where very good at certain tasks while also requiring anti seizure drugs which kept them in control.
IIRC, it was more "intelligence may be a maladaptive dead-end".
The idea that human kind would in its moments of fear and panic reach back and put an anti-social predator in charge is also thematic. In traditional conceptions of hierarchy of "thinking", we would perhaps imagine the self/meta conscious self as being "the top layer", with the layer represented by vampires perhaps being a lower layer (we would imagine it being above "the reptile brain" though). Yet here, humanity (or human command) has chosen to invert the order. The self-awareness layer is capable and does "let go", because while it loves to take the credit for what the mind actually does, it does in fact understand self preservation (generally), and does understand that sometimes, it just needs to... not really be in control.
Final spoilers - and then there's the extra twist which is that the vampire captain was apparently being puppeted by a computer AI system (also implied to be not self aware) the whole time anyways.
So really, we have a pair of non-self aware intelligent systems probing each other. One deploying scramblers, the other deploying the human crew as end effectors.
Can still spin a tale with whatever adjusted sense of self you want without invoking mythical creatures that existed, died off, resurrected, and genetically spliced into humans for space travel.
A long time since I read the book, but I thought the human AIs claimed they could describe a consciousness-optional intelligence, but had not made one. Ergo the meat-puppet controller would have been a conscious AI.
Happy to be corrected on this point because it could partially address what seemed like an oddity to me. There exist super intelligent AIs, but on this incredibly important mission which could define continuing human existence - none of them are in control because AIs make humans uncomfortable. Instead, the AIs secretly operate a meat-puppet predator whose existence makes humans uncomfortable.
> might have some lingering trauma
Why does every character have to have some trauma? Just because the Oscar committee says so?
All of the characters are weird, super humans with their own problems. At one point, the vampire freaks out and attacks the protagonist. Which leads to some plot ramifications. If you are to maintain that structure, you require a teammate to lose their cool at a pivotal moment when it has been established that the team leader was better and more logical than everyone else.
The in-universe vampire explanation gives a rationale for the scenario. This does not hold if you trivially swap out for a different character, so some kind of hard-wired trigger is required.
Since his surgery, Keeton has rebuilt his sense of self around observation of human behavior, extraction of patterns into rules, and used those for his Chinese Room. Thus, “Pod Man.” This turned out to be useful in this rapidly evolving society. But Sirasti/Actual Captain need a witness, a human witness, not just a synthesist. The attack collapses Siri’s Chinese Room — the book says as much — and makes him into a Real Boy. Pain, terror, these are experiences, not translations. Like a stellar collapse of a Matryoshka Brain, the dead end black hole of self-referential, all-devouring, navel-gazing consciousness is left behind. Inefficient and alien to most other intelligences, but what is required when you want to launch a pod back to Earth, Siri inside, not Pod Man.
Once you understand who the Captain really was, well, you aren’t looking at Sirasti at all.