Black Sails is basically a story of one man's regress to his past self (Flint) and other man's progress to his new self (Silver)

I always thought that despite "do means justify the ends" being the topic in S4, both Flint & Silver are actually on the same morale scale, but at different ends.
At the beginning of the show it's made clear that Flint cares too much, Silver doesn't care at all.

& they are moving towards each other/the middles as the show progresses.
When Miranda dies, Flint reaches the point of not caring.
Meanwhile, right around the same time, after losing his leg, Silver reaches the point of caring.

They are both in these states when they end up on the Maroon island & honestly I think it's often overlooked how much impact that singular event has on the both of them.

I feel like they each find something they have been looking for on that island. For Flint it's purpose & for Silver it's his personal connection to Madi.
through these bonds they become able to actually revert back to their original selves.

When Flint doesn't kill Silver on the skeleton island and instead tries to talk some sense into him (much like he did with Hennessey) & when Silver tells him "I don't care", something S1 Silver would have said, for a second it seems like nothing has changed.

But at the same time, EVERYTHING has changed.
The fact that they sound like their previous selves doesn't mean that their journey didn't change anything. It surely changed their perspective.

Silver says he doesn't care PRECISELY because now he has something/one to care about.
And Flint doesn't kill Silver because the war isn't worth his life.

So in a sense, it feels like they both got to try the opposite extremes of their shared scale and exactly because of that understood why they had to 'revert' to their old selves.

The 'reverting' in itself is a violent act for both of them.
Flint was unmade by hands of Silver and by doing so & betraying his men, Long John Silver was also unmade.

So what I'm rambling here about is that in a sense these two men are mirrors of each other. Their intimacy is singular because they are the extremes of each other on the scale they share. And as they are crossing over and meet in the middle, they truly are singular.