Usually the first few fibers will get trapped and splay in every direction on the side you start palmering.
What I do is strip some or all of the fibers on the far side getting wrapped down on the hook shank so none of the fibers get too funky. Sometimes I like to palmer the full feather though and you definitely do get a few fibers all over the place.
That said, David Hughes in "Wet Flies" (great book) argues that having a few wet fly hackles splaying in strange directions probably makes no difference to the fish....so you can just leave them if you want. I tend to agree after fishing wet flies quite a bit the last few months.
Or, you can just pull 'em back and wrap the thread over slightly to force
them backwards. Like this: https://www.google.com/search?um=1&h...gs%3B618%3B307
It depends on whether you're a "tip tie" or "stem tie" kind of guy. Hughes advocates the "stem tie" method, and I prefer it this way honestly....even though I learned to do it tip-first. I like winding thread through the entire hackle for stability.
Here's the method I like (and Hughes advocates) -- scroll down and you'll see a picture of it. http://www.flytyingforum.com/index.p...c=33242&page=2