Consistency is the Clue

Whatever we basically are is how we consistently act.

One cannot act against their nature, they can pretend but eventually will revert to what is most comfortable according to their character.

This has been my observations after many years of being around a narcissistic family structure.

Conversely those who are consistently sweet and kind almost never doing anything unkind and if they do it was without realizing it. Kind people cannot stand the thought of hurting anyone.

1 Corinthians 13:4-8
"4 Love is patient, love is kind and is not jealous; love does not brag and is not arrogant,
5 does not act unbecomingly; it does not seek its own, is not provoked, does not take into account a wrong suffered,
6 does not rejoice in unrighteousness, but rejoices with the truth; 7 bears all things, believes all things, hopes all things, endures all things.
8 Love never fails;"

One cannot be full of self and loving at the same time.