One of the things about writing is knowing the creative limitations. Everything must be believable in the world you are writing about. Certain laws have to be obeyed. In the context of writing historicals, I do believe you have to obey historical laws as well.
After I got my idea for Sold and Seduced, I started to think about it. And suddenly realised that I had a problem --- basically Roman marriage law. Th Romans recognised four types of marriage. In the time period that I write about, in the vast majority of marriages, a woman's hand was not given in marriage. It was sans mano. She remained under her father's or guardian's control. This is why Roman women do not bear the same family name as their husband's. In the very early Republic and then later in the Christian era, Roman women did come under the control of their husbands and were married cum mano, but during this time, it was felt that women would be batter served if the legal guardianship stayed with her birth family. The intention was to make marriage stronger, but actually, it only increased divorce and made families less stable.
Personally I think it interesting that the early Christians went for the cum mano. I suspect Jewish tradition may have played a part, BUT as Roman custom and law prevailed at that point, and there are certain similarities in the wedding ceremony, I find it interesting.
Anyway, I had then had to come up with a reason why after Aro and Lydia were married, they would stay married -- particularly as Lydia's father was not keen on the marriage. In other words, I had to find a reason WHY Aro would insist on a marriage cum mano or with hand.
Once I had accepted the limitation, I was able to work with it, and the rest of the story flowed.
Some writers like to think about total freedom, but actually it is the structure and the demands of the world you create along with the main arc of the story that force you to exercise your creativity.