Pieces of a puzzle

Thinking about compatibility, one always gets the analogy of 2 pieces of a puzzle that fit in together. That is compatibility. Reflecting a little deeper into this analogy, one discovers that 2 pieces of a puzzle are different from each other. If one has a certain slot empty, the other has the ingredients to fill such an empty slot. Hence there differences provide for each other and complete, fulfill each other.
But then why do we sometimes get the feeling that we are looking for someone who is like us? Does the analogy of the 2 pieces of a puzzle, fall incomplete then? My answer is, no it doesn't. Since these 2 pieces of the puzzle, in addition to being different, also have a huge similarity. The sameness in essence! They are same in essence since they are the pieces of the same puzzle. A piece of the puzzle spanning, for example, the sky in a scenic image, will fit with another piece that is a continuation of the sky.
If you take a piece from a picture of a mountain and try to harmonize it with a piece from the picture of a desert, even though they may fit in cosmetically, they will not 'go together'!
A similarity in the basics, in the essence, in the values, accompanied by difference that work towards mutual fulfilment, seem to be the ingredients for compatibility!