So here is the situation so far. With my players ship I am giving them a skilled Navigator because they don't have one in the party. This NPC will be fully fleshed out (I created a full origin path for him) so that he is actually interesting to interact with. The Navigator will rarely be leaving the ship so he wont interfere with most of the players actions. 95% of his job is just to get them safely from point A to B. Anyways, the two most important parts of his origin path are Tainted (deviant philosophy) and Press-Ganged (jealous freedom) and he is from one of the renegade navigator houses.

His back story goes roughly as followed: At a young age he was captured by the Ecclesiarchy from his navigator house. At the time he was showing signs of his strong navigator potential as well as his mutations (Inhuman Visage, and Unnatural Presence). He became a subject of study for several years, essentially tortured by the priests. The priests gave up on learning any more from him and were planning to kill him when a rogue trader came by and requested the release of the navigator into his custody. The navigator learned under the rogue trader and his crew for several years and is now being given to my players. He has sworn vengence on the priests that captured him and hates the Ecclesiarcy in general for allowing such events to occur.

This is where the fun begins. On of the players is a Missionary (although he is currently at odds with the Ecclesiarchy to some extent). Besides the obvious hostile attitude towards the Missionary player I am looking for some other ways in which to bring his background into the adventure. Ideas are appreciated.

Those priests that imprisoned him sound a lot like a heretical cult, not loyal members of the Imperium.

Some random ideas:

- Perhaps the Navigator's drive to found his own house or return his to some semblance of respectivility. A huge undertaking, probably not achieved in his lifetime, but the resources of a Rogue Trader can go a long way, and the return investment for the players would be their very own pet navigators... Could even be a seed for a whole adventure.

- An unholy appetite that the Navigator has for the warp, looking from the viewpoint of 'The Enemy of my Enemy is my Friend'. Sure, the Ecclesiarcy says the warp is soooo bad. Manifests at first as more accurate jumps and decreased traveltimes, but perhaps also in increased or even deliberate problems while in the warp.

- A request to seek out and confront the deviant priests that tortured him so, as the Navigator believes that he is entitled to vengeance. Could be interesting and a play to pitch the Player Priest vs his own comrades in a game of 'who has the right philosophy'. Could be very interesting, though probably not very profitable unless the Rogue Trader is up for a round of 'loot the church'.

Well, first things first, in my books "priests capturing navigators for study" isn´t making much sense. I would have expected them to burn, torture/interrogate him or something like that..

Anyhow:

[Witchthunters]
If the line of said Navigator is a renegade one and hunted and it happens that a member of the family (the npc) was captured, other could be after those family members as well for the purpose of cleaning them from the universe. While it is unlikely that ships will go for lightyears just to catch ONE Navigator, I could imagine that there are some Witchhunters roaming the rim to route out Heresy and Mutants. If they learn about the pc´s ship they could try to confront them and demand the Navigator to be handed out to them. This is of course something the PC cannot do. The choice is: flee and be hunted by this one Witchhunter in the future (and possibly other who learn that the pc are in the area) or fight (which potentially cuts into profits due to the damage and might bring parts of the Ecclesiarchy up against the RT). This all could be stopped by an Endeavour to petition for a "writ of pardon" for the Navigator.

[blood thicker then..]
Somewhere out in the expanse the pc meet another member of the House (on an RT ship or perhaps a privateer). Later, the pc have an opportunity to make profit if they wrench it from the hands of said captain that employs the other Navigator. Things turn hostile. The Navigator of the pc pledges them not to destroy the ship the other Navigator is on. Problem is, the other ships captain is bloodthirsty, headstrong and willing to fight to the death... Social roles are needed after every confrontation (difficulty depends on the players actions). If lost, the Navigator will show his displeasure and scorn by simply making some of the travels take a little longer. Officially, he blames the warp (no-one openly rebels against the Lord-Captain!), but he knows and the pc know and both parties know the other party knows...

[unchecked Mutation]
The Navigator develops some horrible cysts and other growth that threaten his health and ultimately his life. The pc need to find a good medical facility with absolute EXPERTS to deal with this. Meanwhile, they have to keep the Navigator alive and hopefully in acceptable health themselves, cutting away growth of cysts (Medical tests) while they try to find out what this is all about (Scholastic Lore; a job for the Seneschall!) Finally, if they found some Magos Biologis or other Member of a Navigator House who might be able to make a genetic treatment they need to find a way to persuade them to treat a member of a RENEGADE HOUSE. Even worse, the Navigator might not want to be treated by the people the RT was able to locate since he fears "genetic espionage" and that secrets of his house could be uncovered, and stats he would rather die than letting this happen.

Thanks for the suggestions. It sounds like I should change "reasearch" to "extract the secretes of the renegade house". The NPC hasn't been introduced yet so I can still change everything.

if they look like the church and smell like the church then they are clearly deviant mechanicus trying to find a way to "add" the navigator gene to a ship machine spirit or the ships equipment in some way so that they can do away with those pesky mutants that we call navigators