Merely being kind has immediate mutual gratification in mind. CS Lewis has some thoughts on both:
“Kindness, as such, cares not whether its object becomes good or bad, provided only that it escapes suffering…”(CS Lewis)
Contrast kindness with Lewis' reflection on love:
“Love may forgive all infirmities [weaknesses] and love still in spite of them: but Love cannot cease to will [to desire] their removal. Love is more sensitive than hatred itself to every blemish in the beloved…Of all powers [love] forgives most, but [love] condones least: love is pleased with [a] little, but demands all."
- C.S. Lewis The Problem of Pain