Mero Mero no Mi

The Mero Mero no Mi, also known as the Mero Mero Fruit, is a Paramecia type Devil Fruit that allows a range of attacks that uses emotions of lust or perversion to transform them into stone. "Meromero" is an onomatopeia of "to fall down drunk", including being overcome with emotion such as love or lust. In the Viz Manga and FUNimation subs, it is called the Love-Love Fruit. It belonged to the Tenryuubito who fed it to Boa Hancock.

Strengths and Weaknesses
The major strength of the fruit, as demonstrated by Hancock, is that the user is able to transform those who have fallen in love with her into stone in varying degrees by using their "dirty thoughts". Victims that have been completely turned to stone are incapable of consciousness and susceptible to physical damage unless the user de-petrifies them. Petrification can also be achieved through physically striking an opponent, although the only area that is turned to stone is the contacted area, as opposed to the entire body. Inanimate objects are also susceptible to the fruit's power.

While the fruit's powers, specifically the aforementioned technique, use the focused lust of a user's victim to fuel the petrification, if the intended targets have no lust towards the user, then the powers are nullified. This can be achieved either by being distracted by other emotions, such as pain and fear, or by simply lacking lust to begin with. Monkey D. Luffy is the only character seen immune to the effects, though he initially believed the attack aimed at him to be an attack from Foxy's Noro Noro no Mi. Other than that, this fruit doesn't seem to have any specific weaknesses outside the standard Devil Fruit weaknesses.

Usage
Hancock uses this Devil Fruit power to petrify her victims. However, the contradictory story that her fellow Kuja are given is that she and her sisters killed a Gorgon and were "cursed". The Gorgon gave each sister a set of eyes on their backs. Whenever anyone sees the back of her and her sisters, they turn to stone. This story is actually a lie, concocted to hide her shameful past as a slave at the hands of the Tenryuubito. Hancock's Devil Fruit was originally fed to her for entertainment purposes only. Hancock uses her ability, within a conjunction of any feelings held about her, by whomever she wishes to attack. As long as her opponent is not distracted by any other emotions or feelings (such as fear or pain), she can cause anyone of either gender to fall for her, upon which she can activate the full extent of her abilities. This fruit's power is extremely effective, especially given the fact that Hancock is virtually unmatched in beauty, which makes just about everyone easily attracted to her.

Even without the use of any kind of special technique, Hancock can use her great physical prowess to attack in hand-to-hand combat; however, her Devil Fruit gives her the ability to turn anything she strikes to stone.

Attacks

 * Mero Mero Merrow (メロメロ甘風 [メロウ], literally Falling-Down Drunk Sweet Wind [Mellow]): Hancock's signature technique, she forms a heart shape with her hands and launch a beam of the shape. Anyone with "dirty thoughts" (lust) hit by this beam will be turned into a stone statue. The beam's effect can be blocked if the target focuses doesn't have any lust for Hancock, either by focusing on other emotions (as Momonga) or simply being ignorant (as Luffy). Mero Mero Merrow reminds Luffy of Foxy's Noro Noro Beam. This attack seems not to kill targets, but rather put them in a form of stasis, as when Hancock revived the soldiers on the Marine Warship, they kept uttering the end of the sentence they spoke when they were petrified and even carried the same momentum. Unfortunately, any affected persons' body can be destroyed, due to the fact that it is stone. In the FUNimation subs, this technique is called Love-Love Beam . The pun in this technique is that those who are vulnerable to this technique essentially become slaves to it; a reference to Hancock's dark past.
 * Pistol Kiss (銃 [ピストル] キス, Jū [Pisutoru] Kisu, literally Gun Kiss): Hancock is able to use a projectile-like move by blowing a kiss, creating a heart-shaped bullet to fire at her victim by aiming it with her index finger. The pun here is that the kanji for gun (銃) is part of the phrase "jūnotsutsu" (銃の筒), meaning "gun barrel", which Hancock's index finger is essentially serving as, in order for this technique to work.
 * Awaken (目覚めよ, Mezameyo): Hancock blows a kiss at a person or persons previously turned to stone by Mero Mero Merrow, which causes small hearts that wash over them and restore them to their normal state. The pun here is that all accounts from former real-life slaves refer to freedom as an "awakening"; so too are the "slaves" of the Mero Mero Merrow essentially "awakened" from the "slavery" of petrifaction stasis. The added imperative at the end of this phrase is not unlike an order being given; another back reference to Hancock's dark past.
 * Slave Arrow (虜の矢 [スレイブ・アロー], Toriko no Ya [Sureibu Arō], literally Arrows of Imprisonment): Hancock breathes in deeply and kisses out a heart; similar to her Pistol Kiss, but much-bigger. She then pulls the heart back with a hand and, with a pop like that of a bubble, hundreds of arrows, tipped and fletched with a stylized heart design, shoot out and barrage her opponent(s) before petrifying them; the sheer number of arrows makes this move particularly difficult to evade. This technique not only petrifies anyone and anything that it hits, but somehow manages to freeze them in place, regardless of whether or not they were in motion or not (even if they were falling down when they were hit), to the extent that she even stopped cannonballs in their tracks. The pun in this technique is that although the kanji used here (虜) may mean "imprisonment", it can also mean "captive", which is what happened to Hancock and her two sisters after their abduction and subsequent selling into slavery.
 * Perfume Femur (芳香脚 [パフューム・フェムル], Hōkō Ashi [Pafyūmu Femuru], literally Aromatic Leg): Hancock does a handstand and spins around in order to deliver a series of kicks. Anything she hits, including inanimate objects like swords and animate objects such as people, instantly turn into stone and, in turn, break from the sheer force of her kicks. It's likely that she hits the opponent with her thigh as "femur" is the thigh bone. The pun here is that, when Hōkō is written another way (奉公), it can mean "apprenticeship" or, more likely, "indentured servitude"; a reference to Hancock's dark past at the hands of the World Nobles.

Trivia

 * Not knowing that it is actually the power of a Devil Fruit, the Kuja of Amazon Lily attribute Hancock's ability to turn people to stone to a curse that she and her sisters supposedly got from defeating a monster called a Gorgon, hence their title of the Gorgon Sisters.
 * The ability of the Mero Mero no Mi; to turn people to stone, was based off of the ability of the mythic Gorgon to turn its victims to stone simply by looking directly at them.
 * It's implied that the fruit is the cause of the unnatural charm Hancock has on most regardless of age, gender, and species. However, this may not necessarily be the case, as seen when Hancock visited Impel Down and was wearing Seastone handcuffs; and yet, almost everyone in the prison instantly lusted after her, including the usually-deadpan Magellan.