Love Letter

Love letter(共感[ラブレター]; raburetā) also known as Empathy, is a strange ability taught and learned in the Highschool DxD: Яe-birth continuitity. Considered a dangerous weapon that can either start or stop wars and conflicts, this ability is unique for humans or who at least want to understand others with all of their hearts, users usually being people who either went to the lowest level of grief or indifference.

According to Rei Miyama, this ability is a rarity amount 'this world ', and cannot be used by 'protagonists', Ichijou and Evelyn being the sole exceptions to this rule.

Summary
First mentioned by Rei Miyama during their second encounter, he explained to Ichijou that the reason why he was unable to see that Ichijou has also his own problems is because he lacks this particular ability. Later, he said that, for being miserable for his whole life up until now, Ichijou has the potential to awaken said ability as long as he thinks that his problems should be put aside in favor of others.

For being 'a black-hole ready to fill her void with everything', Evelyn awoke her own version of Love Letter, named 'Polar', which is the opposite of Ichijou's own version. It's later revealed that the reason why both can enter in Love Letter so easily it's because of their own 'Absolute Terror Zone' ability.

Abilities
Said by Miyama that can only be used by those who either went to the lowest level of grief, yet yearn for contacts of others, Love Letter is the ability to feel empathy for others, and from there, either undestand each another, or put the enemy off Balance with provocations.

Dubbed 'the ultimate language style', Love Letter enables the user to put themselves on their enemies' shoes, and thus undertand the feelings, hopes, dreams, triggers and senses. From such information, the user can either end a the battle through conversation, or start another one through provocation and teasing. It is noted that such ability can also be used outside the battlefield, in normal chats and relationship managements. Depending on the user, Love Letter assumes several forms of understanding; during all of them, however, the user changes the color of their eyes to they enemies's.
 * TheForms

Minus
The Minus(負[マイナス]; Mainasu, lit. Negative) variation is used by those who suffered great hardships and reached the lowest level of grief, yet, yearns for the affection and the friendship of his peers. In this state, by seeing the world by the eyes of it's victims, the user can understand their motives and hopes, and so, either rationalize with or provoke them. This form also allows the user to pin-point the good part and qualities of the enemy, since 'the ones who sank the lowest can see anything shining as a plus'.

Polar
The Polar(同様[ポーラー]; pōrā, lit. Equal) variation is Evelyn's unique variation of the technique. Since she's still mentally unstable, and therefore unable to undertand the feelings of others, her Love Letter state is more physical than the Minus variation, in which she lowers her stats to the same as her enemies in order to undertand their patterns and fighting spirits during moments of conflict. This form can only be used in the middle of a fight, and thus enabling the user to plan strategies in mid-battle.

Drawbacks
Love Letter cannot be used by those who don't, and therefore can't, understand others, called ' Pluses(肯定[プラス]; purasu, lit. Positive), whom Rei calls 'too good and powerful to even think in understand anybody who's below them'. Rei himself is a Plus.

Trivia

 * This ability is partially based on the 'Styles' of the Medaka Box series.