What is this guy trying to achieve? How do you see his story being resolved?
Does he want the death of all Bretonians or just some? Where does he live - somewhere remote or on his ship?
He can, in something smaller, make his presence felt in other ways. A gunship that captures crew, supplies, for a larger vessel that is rarely seen, if at all ..and word spreads of the true nature of his monstrousness through rumour and tales traders tell of the horrible fate of their passengers and crew.
Re-work the stolen Outcast ship part. It's the weakest part of the story. Stole a ship? Hmm. Stole a fleet? You want to make a splash, go overboard. He could have several ships working for him, and he doesn't even have to pilot or be present in all of them. He could resonably be expected to disguise himself and land on planets in civilian ships.
Age would also bring wisdom. We might call it insanity. But there should be some insight that humans aren't capable of.
A monster in literature has three distinct features:
1) predatory - it strikes without warning where you don't expect it
2) vengeful - it has a grudge that is unreasonable in dimension
3) holdfast - it has a lair where it is at its most dangerous
This character could be a long term addition to the game. Popping up in a busy war-torn system won't get the story the exposure it deserves. What he will get is short shrift from a country at war. Introduce him more slowly.
Just some ideas. I quite like the supernatural horror part. Staying awake for 800 years and living for a lot more means he would know and talk about things that seem odd but would be true - check the Disco timeline. Of course, it would require that some people he interacts with would have to realise eventually that he is something genuinely unusual. So a long gradual development of his presence would work best.
