I was browsing my bookshelves the other day and spotted Mainline by Deborah Christian. I was puzzled, because I had no recollection of this book whatsoever, but must certainly have read it (books don't get shelved until I have). The publication date was 1996, when I would probably have ordered the book from a postal SFF bookseller I dealt with at that time, who used to send an occasional stock catalogue with recommended reads and comments on each book – sadly, long killed off by the online booksellers.
The blurb sounded promising so I duly read it. The plot is set in a very distant future in which humanity has expanded to create an empire of many worlds, shared with alien races. Some humans have developed psychic abilities of one kind or another, and these are marked with face tattoos to warn people of their particular skills – except for some Imperial agents, and wild talents who have so far escaped identification.
Reva is such a wild talent – a young woman who can move between alternate time-lines at will or hover invisibly between them, deciding on which one to enter. A useful talent for her chosen profession of assassin, enabling her to appear and disappear from any particular reality; her ability to achieve the apparently impossible has made her wealthy. She is a sociopath who has kept aloof from involvement with other people, simply changing lines to avoid problems. However, on a visit to her home planet R'debh, a watery world where she endured a difficult childhood, she finds herself drawn into relationships with Lish, a "Holdout" (supplier of illegal merchandise to the criminal fraternity) and Vask Kastlin, whom she believes to be a fixer, but (as readers know) is actually an Imperial agent with his own talents. The threat posed by another assassin, the formidable alien Yavobo, holds Reva pinned to the mainline – the reality she is now in – due to her reluctance to abandon her new friends to their fate. She is faced with one problem after another in resolving the complex situation which develops, and experiences a gradual shift in her priorities and character, eventually being forced into taking drastic action.
This was the author's first novel and was an impressive debut, keeping me turning the pages and reluctant to put the book down. It is not without flaws, however. The story is too crowded with characters and other strange beings such as Borgbeasts and the legendary Ghost Ray, although to her credit I didn't usually forget who people were. Furthermore, I could never sort out what happened to the versions of herself who existed in other time lines which she crossed to. She materialises physically in each line, but also seems to replace the local version. I do prefer such plot devices to make sense within their own context, however wild the concepts might be.
A quick web search revealed that Deborah Christian, who nowadays prefers to use her middle name of Teramis, has been working primarily as a game designer, although she has published three other novels; two fantasies soon after Mainline, and Splintergrate (to be published soon) which is set in the same universe as Mainline.