Meredy is an average tall young girl with a slender, curvaceous figure, light skin, pink-colored eyes, and pink hair that reaches down to the middle of her back, is quite wavy, and is accompanied by a dark brown set of earmuffs. Her outfit consists of a red dress that reachers her thighs, with a golden trim around a deep neckline that exposes a large amount of her ample cleavage with a short skirt and a belt tied around her waist and black colored stockings and brown boots. She also wears a dark, high-collared cloak to hide her identity. After joining Fairy Tail, her pink guild mark is in the middle of her right thigh.
Meredy is usually a stoic, mature, and calm individual when she first appeared. To her enemies, her speech seems almost robotic, as she pauses between words and refers to her mission to "exterminate" and "annihilate" her enemies as the "prime directive", and she even gave the members of Fairy Tail numbers for the order in which she would kill them. When in battle, she also seems to be quite cocky, referring to those she considers weak as trash. Her actual personality, which she displayed on the Grimoire Heart airship as it neared Tenrou Island, is more childlike. She quickly grew excited because she saw that the island was in view, but showed a lack of confidence after Ultear scolded her, as she then hung her head down in an ashamed manner. When she saw Makarov in his Titan Form, she looked both frightened and curious.
Meredy also has an immense amount of passion and resolve for someone her age, as she was willing to kill herself to protect the one she loves.
Seven years later, Meredy not only seems much more cheerful and friendly but is also more modest. This was shown when she kindly greeted Juvia after seeing her again for the first time in seven years and smiling as she did so. Juvia notes her to have also developed a witty sense of humor as well as a playful personality shown when she teased Gray and Lucy with the Sensory Link, and Jellal about his lie to Erza.
Maguilty Sense: The Lost Magic that Meredy uses. It has the ability to make two or more people's senses as one. If one of the people linked with the Magic feels any kind of pain, then the others will as well.
- Sensory Link: This spell allows Meredy to link two different people's senses by using strong feelings of some sort between the two people that are being linked. The linked people are distinguished by a seal that looks like a heart on one of their wrists. The two people being connected to the Caster do not have to be near each other in order for this spell to work.
- Three Spread Sensory Link: This spell allows Meredy to link with others who are linked by her Magic, Maguilty Sense, causing pain and death to be shared by all three of them.
- Maguilty Sodom: It creates teal Magic swords in the air. Azuma and Rustyrose mentioned that the swords are formed from Meredy's incredible faith. Using simple arm motions and sometimes verbal commands, she is able to launch the blades, which then hone in on her opponents. The blades are different from normal swords, as they attack the opponent's sense of pain directly, making it possible to slice and damage a mage like Juvia using her water body. However, the blades can still be knocked away or blocked by rapid and high-force water, such as waves. Meredy is also able to create different varieties of blades.
- Maguilty=Rays: With a flick of her finger, Meredy creates various yellow blade-like constructs around her person. Either by voice command or through gestures, she is capable of quickly sending them flying towards her target like if they were lasers. Pretty much like Sodom, this spell is capable of bypassing the opponent's defenses and hitting their sense of pain, this time though they cause explosions.
- Maguilty Judgement: Meredy creates a pink magical orb which surrounds her hand, she then fires with great speed towards a target. If hit, the orb will be printed on the spot they were hit, afterwards various magical swords will appear above the target and descend upon them. Instead of damaging though, they try to restrain the target by forcing them down on the ground, surrounded by various swords, before the swords charge to create a massive explosion.
Enhanced Durability: Meredy has shown herself to be a durable combatant. She was able to receive several of Juvia's powerful water attacks, and still remained capable enough to push through with the battle.
Great Magic Power: As a former member of Grimoire Heart's Seven Kin of Purgatory, Meredy boasts a high level of magic energy, matching that of an S-Class Mage. When exerted, her magic color is pink.