Who was she - before?

My challenge today is creating a character analysis for two of the main characters in my novel.  As a writer of non-fiction, the idea of creating characters totally from imagination is a huge challenge.  For this exercise, I'm half way between.

My fictional characters are roughly based on my grandparents - my grandfather whom I never knew, and my grandmother whom I only knew as a stern, white-haired old woman.

When I catalog the life events I know about my grandmother - her father died when she was 10; her husband died when they'd been married just 4 years, leaving her with 2 daughters under the age of 3; she never remarried, supported herself and her daughters by cleaning houses, taking in laundry - I can imagine how one might became stoic, humorless.

But my novel happens before all this and I must assume that before life rained down a hailstorm of trials, there was a child who was happier, a young woman with dreams and aspirations.  What was she like? What was the narrative of her childhood? What was inside her from birth? What did she see and learn from her family that positioned her to keep going, to persist in working harder than she likely ever imagined she would have to?

Since I cannot ask her, I can only imagine. Creating a narrative for her childhood - a happier time in her life - all the while knowing the the challenges she will face, the sadness - it's an awesome task.  Wish me luck. Wish me wisdom.