Bisexual in a dream: what does it mean?
Dreams of attraction to a gender outside a person's waking pattern are common, are reported by people of every orientation, and do not settle anything about who the dreamer is.
How do the four traditions read it?
Each reading below comes from a named tradition and a cited source, so you can see where it came from and decide what fits your dream. The four often disagree, and that is the point: a symbol rarely means one fixed thing, and the distance between Freud, Jung, modern research and myth tells you more than any single verdict could.
Freud
Freud held that an original disposition toward both was the ordinary human starting point, which was an unusual position to take in 1905 and is the part of his sexual theory that has aged best. He would not have read such a dream as a revelation.
After Freud, Three Essays on the Theory of Sexuality (Brill trans., 1910), public domain.Jung
A Jungian reading would look at the figure as a figure first, and would allow that a dream can use attraction to say something about a quality the dreamer wants rather than about a person they want.
Our summary of a Jungian reading, in our own words, not Jung's. See Jung, ed., Man and His Symbols (1964).Modern
Sexual dreams are among the most commonly reported types in every large survey, and dreamed attraction does not map cleanly onto waking orientation in either direction. Anyone who arrives at this page worried should know that the research gives them no reason to be. A dream is not a verdict and nobody is obliged to act on one.
Our summary of the typical-dreams literature. See Nielsen et al., Dreaming 13(4), 2003, 211-235.Mythological
Traditions vary so widely here that generalising is useless, and the modern categories do not transfer backwards onto societies that organised the whole subject differently. We would rather say that than tidy it.
Rosmerta Publishing editorial synthesis. Our own words; no quoted text.How can writers use this symbol?
The same symbol, read as craft material rather than as a dream. What it does on the page, how genres use it differently, and what happens when you turn it inside out. Written for novelists, screenwriters and poets who need the symbol to actually work, and it ends with something to try.
In literature
The literature has a long habit of using a dream as the safe place to put a desire the plot would not otherwise permit, which is worth noticing, because it is a workaround rather than a treatment.
Rosmerta Publishing editorial synthesis. Our own words; no quoted text.What it does in a story
It gives a character a private fact that costs nothing and changes everything about how they read their own history.
Genre conventions
Older fiction codes it and denies it. Contemporary fiction states it, and the interesting current work is about the next morning rather than the night itself.
How to subvert it
Write it as entirely unremarkable to the dreamer and enormously remarkable to everybody they tell.
Try this
Write four hundred words of somebody deciding not to mention it, and then mentioning it.
Only the first of these names a source. What a symbol does in a story, how genres treat it, how to invert it and what to try are our editorial judgement as writers and editors, not findings from a body of research. They are offered as craft opinion and should be argued with.