I'll write this post mostly from a personal standpoint.

So, I'm considering that I might be a 9, I did identify as that in the past, but I'm having trouble understanding the concept of repression.

Internalisation: energy directed inwardly
Externalisation: energy directed outwardly
Repression: energy directed unconsciously?

It seems that repression of anger in 9s manifests in terms of keeping in a state of mind that is anger free. But that state of mind cannot be maintained indefinitely. What happens when peace is hindered - is anger expressed explicitly?

I often like to zone out and be totally free of distractions, but if there is noise around me - in particular when someone who should know better is being noisy, then I get angry. I might express the anger explicitly in order to remove the source of distraction so as to return to my state of peace. I would prefer it if I didn't have to get angry and could just be in a state of mind conducive to my intention, but this isn't always the case.

another example:
I consider myself as a "victim" of the mental health system. I'm forced to take anti-psychotics, and I view the whole situation as suppressive and morally abhorrent. So I am frequently angry about this. I would much prefer it if I could just be who I want to be and not be constantly tranquilised and afraid to be myself, but the corruption of the world has overcome me.

In general: an anger at what I perceive as unjust behaviour, particularly when it's causing me considerable amounts of stress (it can be vicarious too of course in terms of anger at the mistreatment of another).

So I'm often angry, but I'm not angry to push myself to be better, or angry as a means of obtaining what I want (for the most part). It's anger about being made to be angry, in a sense. I would prefer tranquility.

Is this how 9s work? Or what is repression of anger? Similarly, when a 6 loses their security, don't they feel fear and want to return to security? Don't repressed emotions resurface when the thing keeping them down is removed?