Elemental Affinity

Elemental Affinity is a stat indicating a unit's resistance to each element.

Description
Elemental Affinity is a number associated to the Fire, Wind and Ice elements. It can go between 99% and -99%, and it modifies the amount of damage one receives from attacks of that element, reducing damage if it's positive(almost completely nullifying it when at max value) or increasing damage if it's negative(almost doubling it when at minimum).

There's usually no Affinity for the Star element, making it act as a neutral element of sorts(can't abuse weaknesses, but can't be resisted either). Disgaea 5 added an Affinity for Star element, though most characters have it at 0 and there's less ways to change it than the other elements.

In Disgaea 2 only, Elemental Affinity also modifies spell damage done(increased if positive, reduced if negative).

Value and Modifiers
Each character class has a set value for their Affinities, increased only by wearing specific Specialists or by effect of certain Evilities. The Magic Knight class usually learns unique skills that increase/decrease the Affinity of units temporarily.

Most generic units(in Disgaea and Disgaea 2 only) as well as enemies in the Item World get randomly assigned resistances: one at 50%, other at -50% and the last at 0. Note that reincarnating said generic units will have these values randomly assigned again.