Light had caught you stalking him, and without you realizing it, he knocked you out and locked you in his closet, because he didn't know your real name and couldn't just let you go.

"Well, I didn't think they'd make someone so weak watch me..." Light said with a mocking smile, as he saw you tied hand and foot, with your mouth covered with a handkerchief.

I would "drug" you with different household liquids so that you wouldn't try to leave or make noise.