1. Knowing each other's habits so well you start doing them yourself.
  2. Knowing every like and dislikes.
  3. Always sleeping and waking around the same time.
  4. Passionate sex always.
  5. Daily discussions about anything. Food. Movies. Books. Etc.
  6. Cuddling when needed.
  7. Goodbye kisses. Forehead kisses. Cheek kisses.
  8. Never fighting.