I studied the archives at her convent, and also the archives here in Lourdes. I found a few stories which show her mischievous character, but these episodes show that she was a normal young girl who strived for radical holiness by entering the convent.
In 1861, at the age of 15, Bernadette had already moved in with the Sisters of Charity at the Hospice in Lourdes. They taught her the Catechism and prepared her for her first Holy Communion, and they also taught her French (before then, she only spoke the local dialect - Bijourdan).
It was forbidden to go into the hospice garden, but there was a large patch of strawberries there. Bernadette got an idea while talking to her friend: "I will drop my sabot [wooden shoe] out of the window into the garden. You'll have to go fetch it, of course, and bring back some strawberries!"
When one of the Sisters in the hospice suggested that Saint Bernadette spend more time in meditation, she responded "Ah well, I don't know how to meditate!"
In that time, tobacco snuff was prescribed for asthma, from which Bernadette suffered. She had a habit of offering it to her classmates as a joke. Once there was laughter in class at the hospice, and the nun asked "What's going on back there?" Bernadette responded: "It's me, Sister. I offered a pinch of snuff to my classmates!"
St. Bernadette was a character, but that can only bring us closer to her. Whenever I pray to her, I often "dare" her, with a smile on my face, to grant my request. I am sure that she laughs with me.
She is a Saint, but she was not always perfect. When she entered the convent, she strived to do penance for her past and for radical holiness. It was her patient suffering in the convent which made her a Saint, and we must never forget that!
Saint Bernadette, pray for us!