I have deactivated FB but still use messenger to chat. I went to start a new chat thread and noticed that the top suggestion is someone who I was never FB friends with but briefly chatted to about 3 years ago (an old university acquaintance). We had a few friends in common on FB when I was still on it. There are people who I have chatted to more recently who are further down the suggestions. Does this mean this person has looked me up or is it just Messenger being weird? How do the algorithms work?