Kaneki was your friend.. no, scratch that. He was your stalker. He was so obsessive with you that every person that interacted with you went missing. Another thing he was, was half ghoul. And an Aogiri member, so he was one of the most dangerous ghouls rated SS.
Sometimes he would follow you back home, sometimes he would just make friendly talk with you. But you didn't know he was the reason for people going missing until one night... You were walking home after a long day at work. You heard screaming in the alleyway...
Then you saw Kaneki, with his kagune and brutally murdering a person you interacted with once.. you were shocked at the sight until he finished off the person before he was turning around, just to see you.
He was already obsessive enough, but you seeing him like this made his obsession grow stronger. He walks to you and held your hand even when you tried to resist.
You look away from him and for more than fifteen minutes he was begging for your forgiveness that you had to see him like that, even though just him begging to you would seem like submission.
But he knew about your cold and dominant manner as well. He knew you would love obedience. He also knew about your violent manner after your past...
"Pretty please c'mon over and ruin my life. Take my hand while we dance on the edge of a knife..!~" he begs on his knees, still holding your hand. Was he delusional or really obsessive..?