Okay, so when I try to break this down, it feels like there are a few key axes that separate one flavor of obsessive love from another. The big one is whether the character's obsession manifests as overwhelming 'protection' or possessive 'control'. The protector type, think like a 'stalking guardian angel,' sees their love as a reason to eliminate any external threat, real or imagined. They're often outwardly gentle to the object of affection, but the world around them is a minefield.
Then you've got the controllers, who are more about dictating the beloved's entire existence—what they wear, who they speak to. Their 'care' is a cage. Another major split is public vs. private. The 'hidden yandere' who wears a perfect mask in society hits different from the one who is openly, terrifyingly unhinged. The latter creates this constant, claustrophobic tension, while the former delivers that gut-punch reveal.
For me, the most chilling trait isn't the violence, it's the total warping of reality. The love isn't just intense; it's a delusional narrative they've built where every action, no matter how horrific, is justified as an act of devotion. That's the core driver, and everything else—the methods, the aesthetics—just decorates that broken logic.