How does the plot develop?

I have been asked by my readers how the plots develop and it's a hard question to answer.
'The Fraternity" has been banging around in my head for some time, so in that, I've been writing down what I've been thinking.
By the same token, as I write ...things happen.
People who were initially quite major character's in my head, have become somewhat minor ..at least for now.
Minor character's or even ones that I didn't originally think of have become quite important in the tale.
One is Trent.
Trent was created in my Sexploit Series - Biker Tales. And honestly he wasn't even in my head when I began writing the short story. It was supposed to be about going on a road trip on his Harley and meeting and screwing his way through California.
But then Trent popped up and I went with it dropping him off at Rancho Hermanos.
However even then I hadn't an a clue he not only would 'pop up' in the Fraternity books, but assume the importance he has. It just seems like a natural progression to me.

Other things like Gil Walker's relationship with Chris Hardway has lasted much longer than I had anticipated through four books and I'm working on the fifth at this time. Something that has captivated me ..and apparently you as well.

I have plans for Gil Walker and The Fraternity, quite a few....but it will probably continue to surprise me as well as you on the detours and directions it will sometimes lead.