Okay, okay. If it will stop the gif madness (as if anything could), Snowbluff can have death by yandere.
Levistus, the Lord of the Fifth and the Prince of Betrayal, is one of the Nine Hells' most infamous rulers. Before his imprisonment in ice by Asmodeus, he was a master of connivance and manipulation, some argue even on par with the Lord of Nessus himself. But more than that, he was an emotional manipulator - he would often seduce others to gain information, or to bend them to his will. One of his greatest triumphs in that regard was a Marilith named Yukina.
Long before his punishment by Asmodeus, Levistus was a commander in the legions of the Hells in the Blood War, directing raids on the Abyss. It is unclear whether Levistus himself led the raid, or whether it was one of his loyal underlings, but when several powerful Demons were captured, tortured, and destroyed, Levistus took the credit. One captive from the raid, however, was spared; this was Yukina, a powerful Marilith general. For a Demon, Yukina seemed cold and calculating; this was a facade, however, for burning beneath the surface was the inexhaustible rage of the Demon.
Levistus spent the better part of a century breaking her. He would torture her, then show affection; he would deprive her, then shower her with gifts. In time, he shattered her mind completely. She became his devoted, adoring slave, his personal Marilith paramour, to be used one day and ignored the next. To him, she was a trophy; to her, he was the entirety of the cosmos.
When Asmodeus finally punished him, that world was shattered. Yukina, having learned to thrive and grown in strength in the Hells, went on a rampage, charging straight to Nessus to confront Asmodeus. But she could never hope to be a match for the Lord of Nessus, and he cast her out of the Hells, using a binding so powerful that she could never return.
Now acclimated to the Hells, Yukina could not return to the Abyss. Haunted by the thoughts of her tormented love, she could find no solace. She drew herself into seclusion in a dark corner of the planes, growing in power and madness, and seeking to inflict her pain upon all of creation.
Yukina suffers from two things: Heartbreak and madness. Put simply, she wants everyone to suffer both. In abundance.
Affection blooms throughout the world, but love is only a step away from obsession.
Faint: Love is in the air! Each day, every intelligent creature in a romantic relationship enjoys a +1 morale bonus to all rolls which aid, serve, help, or protect their loved one. They must succeed a daily DC 2 Will save or take a -1 morale penalty to all rolls in opposition to, or to disobey, a loved one. The morale bonus does not apply to this save. Intelligent creatures not in a romantic relationship do not enjoy bonus or penalty, but feel an odd longing for romance.
Moderate: The heart wants. The morale bonus and penalty for those in relationships becomes +2 and -2, respectively. The DC to save against the penalty increases to 5. Those in romantic relationships must also make a daily Will save, DC 5; on failure, they become jealous, and suffer a -2 to all social interactions, believing any person might be a rival for their loved one's affections. The morale bonus does not apply to this save. Those not in romantic relationships must make a daily Will save, DC 5, or start to fixate on someone as their loved one. If they fail this save three days in a row, they treat this person as their loved one for purposes of this Sign, and gain the corresponding bonuses and penalties, as well as the save against jealousy.
Strong: You are mine alone! The morale bonus and penalty for being in a romantic relationship increases to +3 and -3, respectively, and the DC to save against the penalty increases to 8. The DC to save against jealousy increases to 8 as well, and the penalty to social interactions increases to -5. Additionally, if a creature in a romantic relationship observes someone interacting with his or her loved one, he or she must make a Will save, DC 8, or attack that person territorially; the attack need not be lethal, but the creature cannot stop until the rival is driven off. The morale bonus does not apply to this save. The DC for the save for those not in romantic relationships to develop a fixation increases to 8, and two consecutive failures are sufficient to develop the fixation.
Overwhelming: If I can't have you, no one will! The morale bonus for being in a romantic relationship increases to +5; the morale penalty ceases to function. The DC against jealousy increases to 20. When encountering any creature who has interacted with its loved one within the past 24 hours (to its knowledge), a creature must make the jealousy save or else attack its perceived rival with lethal force. If the creature sees its loved one interacting with another, it must make the jealousy save; on a failure perceives this as an ultimate betrayal, and attacks both the rival and the loved one with lethal force. The morale bonus does not apply to either save. If a creature kills its loved one, it is no longer in a romantic relationship. All creatures not in a romantic relationship must make a Will save, DC 20, upon meeting a new creature of any kind that might be desirable to it. (Standards vary, we don't judge.) On a failed save, they immediately fixate, and are treated as though they are in a romantic relationship. On a successful save, they are immune to this effect with respect to that specific creature for 24 hours. Should a creature remain not in a romantic relationship for three consecutive days, it must start making a daily Will save, DC 20, or die instantly of a broken heart.
In addition to the normal malefic property common to all Elder Evils, Yukina has Overwhelming Affection.
Overwhwelming Affection: Any creature not in a romantic relationship who comes within the range of this Malefic Property must make a Will save (DC 10 +1/2 Yukina's HD + Yukina's Charisma modifier) each hour or become overwhelmed with love for Yukina. They become fiercely protective, and will seek to prevent any hostility towards Yukina with lethal force. If a creature fails this save, it may try again in 5 rounds.
Any creature in a romantic relationship who comes within the range of this Malefic Property becomes convinced that its loved one has betrayed it in favor of Yukina, yet oddly bears Yukina no ill will. Such creatures must make a Will save (DC 10 +1/2 Yukina's HD + Yukina's Charisma modifier) every hour or cease their present course of action and seek out their loved one, to attack with lethal force for the betrayal. If it does not reach its loved one within 24 hours, it may attempt a new save once every 24 hours to convince itself that the betrayal was imagined. The morale bonus does not apply to these saves.
Yukina, very simply, is mad. Upon the manifestation of her Strong Sign, she will personally manifest in the Prime Material Plane, and start marching across the countryside aimlessly. She draws no amusement from her actions, nor satisfaction; she has no overarching agenda or desire. She is simply mad with love and loss, and her madness radiates from her. By the time her Overwhelming Sign manifests, she will have seen enough "love" in the world that it will drive her into a fury; she will seek out population centers and slaughter those who haven't already killed each other out of misguided obsession.