Mary Shelley makes the intimacy with Lord Byron sound almost accidental. In fact,
it was all carefully arranged by Claire Clairmont, Mary's step-sister, who in a bizarre
case of oneupmanship that trumped Mary's affair with Percy Bysshe Shelley, had managed
to seduce Byron two days before he departed England in April 1816. By the time the
Shelley party reached Switzerland, Claire realized that she was pregnant from this
liaison. Although the relationship continued in Geneva, Byron soon tired of Claire
and came to dislike her, so much so that in subsequent years he would see the Shelleys
only on condition of her absence.