Sandra/the 'heroine's past.
Basically after the country had an event that signals the return of the Saintess, they started searching.
Found her.
But when she thought her life would improve, it didn't.
Her real mother died to a disease long ago, and right now despite all the support she's getting from the country it's all spent in vain by her stepmother on alcohols or other vanity shit the stepmom fancies.
The father is a spineless one who don't say anything back and there's 2 bratty brothers (not the 'I bulli you' kind, but more like kids not listening to what she say)
Sandra used to sell flowers to try and help the family income.
Because the bitchmom spent all the money, she could only wear plain cloth.
In fact Frederick even mocked her about 'hey, you smell the stick of commoner?'
She ran away, and was being melancholic wanting money.
Then she saw Lana's ink bottle and how wonderful looking it is.
For a moment she thought "how much is this worth" and picked it up.
Lana returned right then.
Sandra dropped the bottle.
Because Lana could say anything, she panic apologized and wiped the ink with her own dress. (So yes, THAT did happen, just not by Lana's order)
She then ran away in tears, where Frederick show up and was about to mock her again, but went blushing seeing her teary face.
After that Frederick fell for her, gifting her new cloth to replace the dirty one.
From then on she learned that she can use her tears to make men do whatever she wanted.
Then a year later the engagement breaking happen, and her Saintess power also blossomed.
One day she came home with another dress from the prince and found her closet emptied.
She went to confront the bitchmom and the latter (drunk as always)'s like "Fuck you gimme more money"
Sandra went to cry in her own room, then she smelled something burning.
She went to the living room, where her brothers are crying for help, the mother and father asleep.
The two kids played with matches and started a fire.
Sandra was about to go in, then paused..."I...didn't see anything, didn't know anything...I only went out for a walk...and when I came back...everything's on fire"
And then she closed the door.
She went out, washed herself of any soot, calmed her breathing, and went for a walk.
She returned with the house fully aflame, Evan directing people to put out the fire.
She went crying into his arm and spoke of 'what about muh family'
While internally she was thankful of God for finally releasing her from her shitty family.
No more bullying stepmother.
The useless father.
Even the annoying brothers.
One panel of the insanity smile.
"There's no going back anymore"
"I will become Queen, and live a life free of inconveniences"
"For sure"
"No matter what means I must use!"
tl;dr - After long years of living under shitty family, bitch be crazy.