The Sadist and Masochist strategy

Both sadism and masochism are based on attacking vulnerabilities.
One is identified with the vulnerability in themselves,
The other is identified with the strength in themselves.
Accordingly, 2 strategies are used to end the threat to their identification.

For the sadist, the strategy is: 

To preemptively attack their vulnerabilities, or prepare for doing that,

So that the other is prevented and disabled from attacking yours.

This is the strategy of sadist/predator mind.
It is weakness inside, strength display outside.

For the masochist, the strategy is:

You take it on yourself to attack your own vulnerabilities and try to end them,

And remove all traces of them.

This is masochist/depressive mind.

This is the attempt to preemptively kill off all needs,
By your own violence towards them.

Now you expect violent from others, prepare and brace for it, and thereby try to stay immune.

But the root for both cases here is: The idea of "EXPECTING" the same things to happen.

What unites the sadist and masochist is = the deep expectation to be attacked/rejected etc. coming from the deep memories of the same from the past.

The responses to this can be complementary because of opposite identifications.

The masochist is identified with strength, and therefore works to remove his vulnerability - in preparation or in reaction.

The sadist is identified with vulnerability, and therefore works to fight all threats off - in preparation or in reaction.

Since this expectation seeks to prove/validate itself again and again,

It seeks/attracts the same circumstances/people to confirm and justify this again and again.

So it is a vicious loop that has a strong gravity of its own,

Which keeps it constantly spinning, and repeating itself in one's experience.