Before you read the actual story, you should be aware of some things first.
Sunless = Caelus
For those who don't know, Sunless is the protagonist of Shadow Slave, while Caelus is the male protagonist of Honkai Star Rail. In this story, the two characters will be considered the same person. The best way to explain it would be Sunless, but with a few… traits that the Trailblazer displays within HSR.
(Those of the silly kind.)
As for how the two series, it would be a merger of the two with certain major Shadow Slave characters cut out. This is surprisingly not too complicated, since most of Shadow Slave takes place in the Dream Realm, while HSR takes place on other planets. Basically, imagine Honkai Star Rail, but with the Dream Realm and all related lore. Earth is mostly abandoned by anyone who has the financial ability to go to another planet.
Some major differences I am making would be the timeline of certain Shadow Slave events, and fitting them into the timeline of HSR.
The events of both series will be occurring, with certain things changed or moved. I've currently only planned until the end of Penacony, with a specific arc from Shadow Slave slipped in.
This will most likely be a harem, but it will be a relatively minor part of the story.
As for HI3, I haven't played it, and will keep things the same as they were in HSR. No changes to Welt or any HI3 associated lore.
Both HSR and Shadow Slave are ongoing series currently, so the amount of material I have to work with may limit me. I'll try my best to make stretch out the arcs, with at least 100k words for each of them, but if I do catch up(to HSR in particular, since Shadow Slave is much further along), then the story would have to be put on hiatus for awhile. I do not want to have to make new content from scratch lol. I'm simply not creative enough for it.
Assuming that I can continue this story for awhile, you can expect an upload of a chapter every week or two, ideally with a few thousand words each. I will be spending a lot of time editing the chapters to reach my standards.
I hope you guys enjoy the story, and of course, there will be spoilers for both series.