To pants as a writer is to fly by the seat of your pants. That is, you’re allowing the characters to lead you rather than the other way around. A writer who does this exclusively is called a pantser.
Then there are planners who meticulously map their whole novel from start to finish. A version of this is those who identify all the key scenes of the whole novel, write them individually, and then move them around into whatever order seems to work, like fitting together the pieces of a jigsaw.
When I began the fantasy novel series I certainly started as a pantser, though with elements of planning. I don’t think you can ever pants your way through without, for instance, knowing the ending. I always know from the start where a story is going to finish up and I think that’s imperative. Beginnings are a different matter and often change many times before the right starting point emerges. I must have tried out at least ten different beginnings for The Courage Game.
There is something magical about pantsing. The characters take on a life of their own. They argue with you. They object to something you’ve made them do. You see them so very clearly and physically as they emerge and take on detailed reality. But if you do too much of this method you can also be led by those characters right up a narrow cul-de-sac. With no way back. Then this method becomes a tremendous time-waster as you struggle to get the characters out and onto a sensible road that is actually leading somewhere.
So nowadays I blend the two. I’ll often explore a character by pantsing. And also often, when writing a scene, I’ll find myself coming up with something totally unexpected. Of course, that’s classic pantsing. The character has decided what happens next and you’ve gone along with it. I don’t let it run away with me though. If a character is turning skittish and wanting to gallop over the hills, I rein it in, allowing it only a little leaway, and steer it through the proscribed gateways. But not always. There are moments …
… for every writer knows there is a god of pantsing, call it a Muse as the Ancients did, where moments of genius occur for a while and the prose just flows. Those moments of pure pantsing are like flying. It flows out of you, a whole page sometimes, and that particular page never needs alteration. That is when I know I’m writing from some well deep inside me, without thought or planning. It is a kind of magic.