Yandere and Tsundere

Hi all!! Today, I'll talk about yandere and tsundere! Kyaha!
First of all,
What is Yandere?
Yandere is a portmanteau of two Japanese words yanderu, meaning to be sick, and dere dere, which is defined as exhausted or lovestruck, but in this case used for "lovestruck". The word was development from tsundere which describes a character who is both hard-nosed or moody tsuntsun and the aforementioned lovestruck. The sick portion was added when a new layer of romantic obsession came about beyond normal tsundere (where cool emotions were warmed and nurtured towards akward and sexualized tension) where seemingly normal displays of affection become mentally dilapidated (i.e. kidnapping crushes, poisoning food that is to be eaten by a romantic rival, or forcing the romantic interest to the commit shinju.

What is Tsundere?
Tsundere is a Japanese charcacter development process that describes a person who is initially  cold and even hostile towards another person before gradually showing his or her warm side over time. The word is derived from the terms tsun tsun meaning to turn away in disgust, and dere dere meaning to become lovey dovey.