Nerdy yapper

Prison

After his vivisection, Heinrix gets thrown into prison. I very much doubt they would simply keep him in the castle or house's dungeon; instead, I think he gets thrown into a specific psyker prison. Everything else would be too dangerous.

I have this idea that the prison is built over/near an ocean so they can drop the building with the psykers inside it if something happens. He hears the ocean and the constant crashing of the waves against the shore, but doesn't see much in his little cell. I have a bit written about it here in my one-shot "Accursed".

I imagine he is alone in his cell and doesn't really see other inmates. He is also not getting any visitors - neither his parents nor his sisters. His little sisters wanted to see him again, but they had no way to reach him, and for his parents, he was basically dead.

To keep himself sane, and because it brings him a little comfort and normality by following his routines, he would try to continue his training. Going through what he had learned, mental exercises, but also practical ones, warm-up, and movements for sword fighting, even if his dominant arm is not moving. He works hard; he doesn't want to forget, and he doesn't want to give up. Like his later self, young Heinrix is determined and strong-willed - and now also praying fervently. Not just because it was part of his training and protocol; now he believes it, desperately seeking a new purpose, answers.

Black ship

The black ship arrives - he is still a child or adolescent, so I think he doesn't spend that long in prison, maybe 0,5 - 1 year. Since I believe he was still a teen when he arrived on Terra, I don't think he spent that long on the black ship either - again, maybe 1-2 years. He was quite lucky that way since this could easily have taken much longer.

This would also mean that wherever Guisorn III is located, it isn't that far away from Terra (the black ship would likely not go directly to Terra until he was lucky and they were already "full", but visit some more worlds on their tour). I am not that familiar with the different segments; it could be located in the Calixis sector, and that is also my head canon, but of course, it doesn't have to.

I think he would again try to practise, but it is even more difficult here because there is even less space and the prisoners are slightly sedated, so he is tired and often exhausted. At first he was happy to not be alone anymore in the cell and even met some other psyker inmates from Guisorn III, but he wasn't able to connect with them as he had hoped for, and soon already wished to be back in his lonely cell, as the sounds he heard and the suffering he had to witness were nearly driving him insane.

Sanctioning

He arrives on Terra and gets sanctioned. We don't know how long it took, but there is a Primaris psyker in the novel Witchbringer who spent 5 years there. But it doesn't mean that everyone takes that long. I would not expect it to be faster than 3 years. So 3-5 years is also my head canon for him.

So he would be around 17-21 when he passed his trial and was sanctioned.

I do think during the years he would have managed to heal his paralysed arm and maybe, seeing that he had potential and was already training, he would also have received further sword training during this time, with the idea to form him into a battle psyker or even primaris psyker, though he only ever mentions becoming a psyker/sanctioned and never that he had been a primaris psyker.

Administratum

"There was a time during my earlier years of service when I performed the duties of a secretary in charge of logistics reports at a local Administratum office.".

The question is what he means by earlier service - to the Inquisition? Maybe back when he was a simple acolyte, he was sent there working as a spy? But somehow I doubt that; Xavier wanted him for his powers, as a torturer, and why would he "waste" him then in the Administratum when other people would be better suited? At least, Heinrix doesn't really strike me as a professional undercover agent.

"No. First, I was accorded the status of a psyker fit for service in the Imperial Guard, where I then spent several years."

So I do think he means his service in the Guard. Maybe there was a time when the fighting was over or paused, and the Guard supported the planets' administratum because they relied on it for resources, etc. I don't think he spent a long time there; my head canon is 6 months to a year.

Imperial Guard

I am not sure whether any stable battle psyker is becoming a Primaris psyker or not; at least, it is my headcanon that he's fighting with both his powers and a sword already. He has the knowledge from his childhood, and I think it might be a bit late if he would only pick it up again years after joining the Inquisition. So I picture that happens earlier.

Since psykers are usually despised and hated, it would have been difficult for him to find friends in the Guard; while we know he was and is able to heal himself to some extent, I think it is more difficult with others; for example, he says when we first meet him that "...And extracting blade shards from a person's stomach is beyond my powers." We do see him heal a dislocated or broken arm easily, so I think he could have been helping with healing to some extent at least. It could have helped him earn some respect and acceptance.

I also think that he is so opposed to the Aeldari that it is more than just normal Imperial and Inquisitorial dogma/brainwashing (even in the Ordo Xenos). I have the feeling it is a bit more personal. This is why I wrote this oneshot "Suffer not..." where he is on his last mission that also brings him the attention of the Inquisition.

During his service, I think he would have come into contact with different regiments of the Guard again, or at least with planetary defence forces. I can imagine that he occasionally relied on their support during his missions.

Joining the Inquisition

Eventually, Xavier notices him, and he joins the Inquisition as an acolyte. I do think he spent 3-7 years in the Imperial Guard, and since he said he spent decades in the Inquisition, that should be at least 20 years. I imagine he was 25-29 when he joined.

His augments had to be removed - likely so they would not hold him back and he would be more powerful. Now, I am not a native speaker, Heinrix says: "When the Lord Inquisitor took me out of the Guard, he had me remove the augments installed in psykers when they become sanctioned." And that does sound like he himself had to do it.

I am not sure if the wording would allow that Heinrix might go to a chirurgeon to get it removed. While I can imagine it was also a test, I think there was some sort of time pressure that led Heinrix to remove it himself, because no one else was available to do it for him. Because, for a test, I doubt Xavier would waste such a rare resource (biomancy seems to be rare, at least based on a lore check in the game) just to see if Heinrix can vivisect himself. He could have tested his powers or resolve in different ways.

That is also a one-shot I eventually want to write, because I also imagine it had to do with something Xenos, maybe even Aeldari related to foster his hate, but in any case what @lordcaptains had written here is quite excellent.

He said it took him years to repair his eye and that he could see as well as before. He started it somewhere after joining the Inquisition, it doesn't sound like it happened right away. "But I decided I would be more useful if I could start to look more like a human again".

It almost sounds like an excuse for his power usage - and I have written about this before; for him as a torturer, there was no need to look more human, quite the contrary. He might have already had a career in mind, but I think it was a mix of trying to be more than just a torturer, which I think he didn't quite enjoy, and also for himself, to feel better, to have a bit of control over his life again. But that is something that clashes with what he was told - that pain is inevitable, that you should not wish for a better lot for yourself - only to serve. So I think it makes sense that he was focusing on this thought, that he is doing it to serve better, until eventually he believed it himself.

Ah - and I think his last name, "van Calox", was given to him by the Inquisition. I saw on a post (sorry, I don't remember who it was) that van Calox might have resulted from Calixis Sector + Ordo Xenos, and I like this idea, and his name fits it very well. I can't imagine someone would have already, during sanctioning, given him this name - there must have been many deaths during the sanctioning, so I doubt they would go through the trouble. I would rather expect them to give psykers just numbers.

I also like to add, and no offence to those who see it differently, but I don't like when Heinrix is compared with a dog - he is loyal, yes, and of course he has to follow Xavier's orders. We all would want to survive; though I think it is also more personal because he is both his teacher and also the reason Heinrix has received what he perceives as a better and more honourable role. And he had allowed Heinrix to heal himself and to start his career. It is no surprise Heinrix is thankful and maybe even sees a stern father-figure in Xavier. It doesn't look to me like Heinrix had a lot of good connections to the other acolytes or other people in general - aside from Emelina, who was supportive.

Both xenos and cultists will frequently call Imperials who believe in the Emperor "dogs". So it comes up a lot, but while I don't think Heinrix is very ambitious and seeks to become a leader himself, we even see in the game that he is not just following Xavier's orders. He doubts him, does not follow all his orders (like with the Guard on Footfall), and even challenges his authority (at the end and even if not romanced). He is not simply a dog that follows loyally Xavier until the bitter end. That he also tries to excuse Xavier's actions is even why I think he wasn't looking forward to replacing Xavier and only does it at the end (depending on RT's action) because he feels it is his duty.

Kasballica

It sounds like Heinrix was active in the Calixis sector - he mentions the baroness there (I do think that part is true, since he is usually not outright lying, but as he said, it was a fling and I am sure she started it), and when Hieronymus talks about his home world, Heinrix directly asks if it was located in the Calixis sector.

The Kasballica is also present there, and with him being in the Ordo Xenos for sure, he had run-ins with them too and then, of course, in the Koronus Expanse. While it seems he was busy travelling and working mostly alone, he had been several times to Footfall (at least 2 times he had visited the Liege) and knows about Ryzza. He also says that they have the Kasballica monitored.

Koronus Expanse

Around 10 years ago (a bit less, I think unofficial info from Owlcat if they haven't changed their mind about it was 5-8 years or so and Achilleas also said he had the "accident" that burned him 5 years ago) Xavier + his retinue came to the Expanse to investigate claims about tech-heresy (Amarnat) but then found a lot of other issues, including the cult.

"To be honest, I'm not even certain that the people I know are still alive. I used to work with other acolytes of the Lord Inquisitor, but in the Koronus Expanse, I have been working alone."

So Heinrix spent years alone (at least without other acolytes), hunting the cult but also keeping an eye on the Kasballica.

Already in early act 2 Heinrix tells RT about Achilleas and calls him one of his observers; so maybe Xavier asked him to take him over during their talk on Footfall before Heinrix rejoins RT or even before.

The question is whether that means Emelina was already sent to Phton IV. She could have spent years there before the attacks started, so I think it is possible.

I also count Achilleas among the acolytes Heinrix used to work with but hasn't in the Expanse. Quite possible he only saw Achilleas on Dargonus again after years.

So, that's it so far. I hope that was what you had in mind? Though maybe it got a bit long; sorry.