@Vrish i have heard that Nandi overheard a convo between Mahadev and Parvati,and he is the one who wrote Kaamsurtra,but it originated from Mahadev and Parvati...thier love sagas are
intricately descibed in scriptures,not to forget many scluptures and pictures of ancient times
Kaam means desire/lust/passion,Kaamdev is the God of desire and Kaamsutra is the Book on activites of desire!hence the name