And here's where the pantser fun kicked in. Without belaboring scientific fact--like atmosphere and temperature and gravity--I created worlds where those elements are addressed with an appalling disregard as to whether or not they could be done. Domed planets, after all, make everything possible.
And then the characters took over as they tend to do in my stories. I discovered that my heroine has a domineering father yet cannot resist matchmaking for other people. My hero is a successful businessman and philanthropist who wants what he wants when he wants it. And what he wants is the heroine. Duh!
Haven't decided what the "black moment" will be. Probably he'll insist she marry him and she'll refuse. Probably--because not being a plotter--I don't know yet.
And that's the adventure of being a pantser!
BTW: If you're going to be in the Sacramento, CA area on October 3 and/or October 24 contact me for where and when I and several other local romance authors will be signing. firstname.lastname@example.org