seats – bought 2 tickets Lufthansa – a person can not travel – free seat next to me?

I bought two Lufthansa tickets for a round trip trip from Europe to Asia (round trip via FRA, return via MUC). I've also booked two adjacent places and paid for it all.

Now the second person can not join me.

  1. And if I'm still recording in the second person – do I get an empty seat next to me, as I originally booked?
  2. Will Lufthansa understand that the second person did not board the plane for the first leg towards Munich and invalidate the second seat on the long-haul to Asia?
  3. Will Lufthansa also cancel the return ticket if the second person has not even traveled to Asia?
  4. Could this get me into trouble?

Background: As the tickets are not refundable, I would at least make the most of it.