This feels like the friend/emotional equivalent of a "Help Vampire" -- someone at work who is constantly asking for help. A /very/ distant friend/contact who is pinging you once every 1/2/6/12 months (thank you crontab!) are doing nothing other than "keeping a contact list"... while sucking blood from your neck. If they are an extrovert and you are a introvert, the exchange is not zero sum!