Mary and Shelley's story is quite the teenage emo drama:
"On 6 July 1814, after Shelley had signed papers securing one such loan, part of which was to go to alleviate Godwin’s financial difficulties, he went for a long walk with Godwin and told him about his and Mary’s plans to form a union. Given Godwin’s advocacy of free love in Political Justice and his openness about his relationship with Mary Wollstonecraft before they were married, Shelley and Mary probably expected Godwin to give his blessing. Instead, Godwin was outraged and tried to separate the two, giving stern warnings to his daughter and Shelley. Shelley was barred from the house and Mary was told to cease all communication with the poet. Mary declared she would be faithful to Shelley, as she could love no other, but agreed not to see or encourage him.
But this was not the end of the matter. One afternoon after their forced separation, Shelley rushed into the schoolroom and said ‘They wish to separate us my beloved, but death shall unite us,’ before giving Mary a bottle of laudanum. He was also carrying a pistol. ‘This shall reunite me to you,’ he said.
Mary calmed him down and he left, but shortly after a midnight ring at the doorbell awakened the household to the news that Shelley had taken an overdose of laudanum. The Godwins rushed out to save him but Mary stayed at home to fret. He survived the attempt."
Now, can we get to the science bits, please?