A valuable and basic definition of morality might simply be “clear signaling.”
If I harm you, I am messing with your signaling, making it less clear. If I deceive you, I am doing the same.
If my own internal signaling is unclear, confused, or contradictory, I am probably going to cause harm to others whether I mean to or not.
If we see humans as signaling networks at various levels of clarity or confusion, we can remove terms like self, personality or ego. “I,” then, am a system or network of signals that interfaces and interacts with other signaling networks.
By extension, there is no need for terms like “narcissist” or “abusive personality” or any of the other many, many words we normally use to describe human signaling networks.
For example, we can see that each human does social management within their own signaling system and as that system interacts with other human signaling systems. We compose a signaling system that we want others to see and then display it.
When a person often uses social signaling to manipulate, control, or deceive others, we can say they are doing malignant or immoral signaling instead of saying they are “narcissists” or “abusive personalities.”
The advantage of removing those traditional terms that assume an intentional personhood (narcissist, etc.) is we can see much more clearly what is actually happening.
With respect to narcissism, we can clearly say what a “narcissist” is. When narcissism is redefined as a signaling problem, we can also see that many narcissistic acts are done out of ignorance more than “selfishness.” People believe that they are supposed to be selfish or secretive or withhold important information simply because they do not know another way to act or have had long experiences with others who signal in those ways.
Of course, all of us manage our signaling systems to put us in a good light, at least to some extent. Refraining from gross behavior at the dinner table is a form of manipulating the signals you send to others. Since that is objectively a kind act, it is not narcissism.
Signaling integrity between adult friends is rarely perfect or even very good. Not because many of us don’t want that, but because we don’t know how to do it. Rather than make virtually all signals clear through a technique like FIML, we are forced instead to use off-the-shelf cultural norms to communicate our “personalities” to others.
Besides the few crude markers like punctuality, basic honesty and reciprocity, basic pleasantness, etc., it is very difficult to know another or even oneself without detailed control over the signaling we do with them.
If morality is seen as fundamentally a signaling issue, then the soundest ethical position would be to make our signaling clearer, more honest, less manipulative. Clarity depends on detail. In this light, we can say that there is a sort of moral imperative to do FIML or something very much like it.