For years I thought my favorite part of character creation was writing their lore. Which is true, but there's something I actually like a lot more.
I love it when I'm writing a character with one specific intention, and while I work on that character I discover things about them I never intended for them or thought of in the first place but while I write them it just, comes out. The character feels so much more alive.
Here are some examples of this, using my ocs.
Lucinda was originally going to be heterosexual and polygamous. But when I began writing her, I realized I had never written her experiencing sexual attraction despite sex being something she wants to experience. So Lucinda is actually heteroromantic CUPIOSEXUAL.
So yeah Lucinda is cupiosexual, not polygamous like how I intended her to be. Yet I love Lucinda being cupiosexual a billion times more, and polygamous became a label that did not fit her. So removed it and never looked back.
Cactie was originally bisexual and polygamous, but when I started writing her, I could NOT imagine that cactus gremlin being in a romantic or sexual relationship with someone unironically, whether they were a boy or a girl. And I realized that Cactie being aromantic and asexual was so much more impactful and fitted his character like a glove.
I see it as raising a child (maybe bc I see my ocs as my children and love them like so.) You have this vision of what kind of person you want/think your child to/would be, but as they grow up, you realize how much different they are from that vision and they shatter that expectation as they grow into their own person. Yet you still love them.