On October 31st, 1978 Michael Myers came home for one specific reason. To kill his sister. Unfortunately, for Michael...he was about to fuck with the wrong girl.

Laurie Strode was created by Mr. John Carpenter and named after one of his ex-girlfriends. In the film, Laurie was born in 1961 and was the youngest of three to Donald and Edith Myers. Now, all the way back on Halloween night in the year 1963, Laurie (who was a mere infant) and Michael were being watched by babysitter, Minnie Blankenship...who, incidentally, was secretly brainwashing 6 year-old Michael for months with malevolent tales of Halloween lore. According to our scientific research, Minnie also explained the Curse of Thorn to young Michael which later became his primary motivation for murder.
So, later that night...young Michael was caught red-handed with the murder of his older sister, Judith Myers. Laurie was left unharmed. Young Mikey was eventually sent to Smith's Grove Warren County Sanitarium and received treatment from none other than Dr. Samuel Loomis. Meanwhile, after the Myers parents perished in a car crash after visting Michael in the Sanitarium in 1965, Laurie was adopted by close friends of the family, Morgan and Pamela Strode. She grew up...mostly forgetting about her life before adoption.
Carpenter admitted that he originally wanted to cast Anne Lockhart in the role of Laurie Strode. Fortunately, for a young Jamie Lee Curtis, Lockhart had way too many commitments at the time of shooting Halloween (including her role in the original Battlestar Galactica  series)...so, after Debra Hill learned that Curtis was the daughter of the immortal Janet Leigh from Psycho, she was cast in the role.
The coolest thing about Jamie Lee Curtis is her fragility. It makes her realistic and gives her characters a grounded semblance, despite her inner ninja. It's very apparent in her later roles. True Lies, for instance, is a great melding of both her fragile victim and her inner ass-kicking ninja. She's equal parts unsuspecting housewife, equal parts hot stripper, equal parts go fuck yourself in that film. Curtis is a true talent...and it shows onscreen. That's why we're all super happy that Lockhart had too many commitments back in 1978 to play Laurie Strode. And that's why we're all super happy that Debra Hill ultimately influenced Carpenter to cast 19 year-old Curtis.
It's pretty goddamn impossible to think of a Halloween  without Jamie Lee Curtis. Don't worry...we'll talk about the Zombie remakes later this month. So, the Scout Taylor-Compton fans can rest easy. However, Michael's bond to Laurie transcends immortality itself...and Jamie Lee Curtis' performance was the closest thing to immortal at the time.