Someone whom you would talk about.
Someone you'd invite for a trip, beer night, hockey match or something like that.
Someone who's personality you would think about.
Someone who you'd thought of as a person, not just nobody.
Someone who's absense you would note without having to check it out from a spreadsheet.
Someone who's wishes you might want to consider.
Someone you would plot against
The monkeysphere article was interesting. It opened up the idea that the world is an adventure, things are not under control. Exhilarating!