This article is from the X-Men Comic Books FAQ, by Kate the Short (email@example.com) with numerous contributions by others.
Danglers are the racmx term for juicy bits of storyline that are raised
in the comics, and then... never show up again. For example, if Storm
receives a mysterious package, and a big deal is made of what might be
in the package, and then the package and its contents never show up
again, that's a dangler.
Danglers happen for a few reasons. Sometimes, a writer is juggling so
many plots that he or she neglects to pay attention to one of them. By
the time the writer remembers the plot point, it's probably no longer
interesting to the readers, so the dangling plot thread is just left to
dangle, instead of properly being tied off.
In other instances, the editorial staff creates danglers. Sometimes a
writer really wants to finish a storyline, but the editors realize that
the storyline is dragging and the readers are losing interest. In that
case, the plot threads are just dropped while the writer needs to work
on new plotlines. A great example of this is the X-Men Revolution arc
that Chris Claremont was writing. He had every intention of telling
readers what happened to Kitty Pryde after she disappeared, but the
editors asked him to take the plotlines in a different direction, so
readers will never know where Kitty actually ended up between the space
station and college. A change in writers is often accompanied by a
healthy amount of danging plotlines. Obviously, new writers have ideas
about what they want the X-Men to do, so they usually don't bother to
tie up the plot threads that a former writer can't finish before leaving
Finally, there's the six month gap. This editorial device has been used
a few times by Marvel staff to give new writers a "clean slate" after
ending a major storyline or before beginning a new direction for the
line of titles. Such a gap was used after the Age of Apocalypse. Rogue
had absorbed Gambit's powers just before AOA, but now it was supposedly
a few months after everything returned to normal, and the characters
had moved away or hit the road to deal with various problems. We never
really saw what happened in-between the end of AOA and the beginning of
Rogue-on-the-Run; we just knew that Iceman had taken after her.
As a second example, the X-Men "Revolution" concept at the time the
X-Men movie was released was designed to return Chris Claremont to the
team books, as well as letting other writers take over struggling titles.
To allow the writers to bring in their own ideas, the first issue of a
new writer's plot would feature the teams and characters as if six months
had passed. Often, plotlines dangling before the gap were left dangling,
and new twists that supposedly occurred "during" the six month gap would
sometimes become danglers as well, if the writers didn't get to explain
the plot before editors requested rewrites or assigned a new writer to
the book. The power switch between Psylocke and Phoenix is one example.
Is there a solution to danglers? Probably not. Writing to request an
explanation of a dangler might remind the editors that a juicy plot
device is available for writers to use, but most of the time the books
will take whatever shape the current writers and editors want.