Arietta plays with her adopted siblings as her Mommy looks on.
Arietta was born on the Island of Feres. While she was still just a baby, the destruction of the nearby Isle of Hod caused a massive tidal wave that flooded Feres and killed all of its citizens. Arietta was the only known survivor, washing up in a basket on the shores of Malkuth. There, she was found by the Liger Queen, who chose to raise her alongside her own cubs.
Arietta had to be chained up to keep her from attacking other humans.
Five years later, she was discovered by Van and taken in to Daath. Because she had never had any human contact, she was wild and animal-like, and couldn't even speak. When Van introduced her to Ion, he developed an interest in her, and he became the one to teach her the human language. Due to her time growing up around monsters, she retained her ability to understand their language and communicate with them.
Ion teaching Arietta how to read and write the Fonic Alphabet.
Arietta was very close with Ion, becoming completely devoted to him. When she agreed to become his Fon Master Guardian, she swore she would do whatever it took to protect him, even at the cost of her own life. However, Ion was doomed to die at a young age, as foretold in the Score. Working together with Van, he and Van devised a plan to override Yulia's Score by creating a replica -- thus, even though Ion would die, "Fon Master Ion" would still live on.
But because replicas don't possess the memories of their originals, in order for the switch to be believable, everyone close to the original Ion had to be removed from the replica's side... including Arietta. Under the guise of being promoted, Arietta was made a God-general to serve under Van, while Anise took her place as Ion's primary Fon Master Guardian. Her ability to communicate with and command monsters made her an asset on the battlefield, and she was very proficient with Fonic Artes as well.
Arietta reacting to being treated like a stranger by "Ion".
But Arietta couldn't just let go of Ion. So strong was her devotion that Van feared she would take her own life if she knew the original Ion had died. And so for two years she pined for him, directing the bulk of her frustration at Anise and blaming her for stealing Ion away from her.
Ultimately she ends up aiding Van in his plan to rid the world of the Score, even at the expense of the humans currently living in it. Her only condition is that Ion won't be killed, which Van promises her -- after all, the Ion that still lived was a replica, which fit into Van's plans perfectly. Thus, Van was easily able to manipulate her for his own purposes.
After the replica Ion is killed by Mohs' schemes, she challenges Anise to a duel to finally settle things between them. The party wins, and Arietta dies without having ever learned the truth about what happened to the Ion she knew.
Ligers are a species of monster on Auldrant. Like all monsters, they hatch from eggs and share a common language. Although Arietta can understand him, she can't actually speak the same language (given she's incapable of roaring and all), so instead many of her monster friends have picked up on human words, allowing them to communicate. In Tanagura, Liger can understand most of what is spoken to him. Whenever he has a chance to speak, either due to an event or when communicating with another creature who can understand his language, his voice sounds rather regal (partially due to him having served under a Queen, but mostly because I thought it'd be funny).
In terms of vocalizations, the sounds he makes are similar to that of a tiger, although significantly deeper. This is most evident when he's happy, as instead of purring, he makes chuff noises. When it comes to roaring and growling, it's something of a cross between a tiger and a lion -- or like an actual liger!
Reference drawings of the Liger Queen, showing details and height comparison to Luke.
Liger was born when Arietta still lived with the Liger Queen. It can be assumed that Ligers live fairly long lives, as the Liger Queen was still bearing offspring when she was killed by the party and is shown in a flashback to have already reached her full-size when she found Arietta. Arietta estimates Liger to be around 13 years old.
Although Liger can understand human names, he can't repeat them because of the limitations of monster language. Thus, he refers to every human he meets by a particular nickname that represents their real name. Notable examples include Spicy Human rashness, Human Brother deathscore, and Tall-human redzone. Arietta is usually refereed to in third person as his Late Queen's Human Child. His own name is impossible for a human to pronounce without roaring, so he doesn't mind going by Liger. If someone were capable of understanding him, they would hear his name as Raoru, but he'd probably judge them for saying it with a human accent.
Ligers are very powerful, capable of tearing through metal with their claws. Due to her own small size, Arietta regularly rides on Liger's back, though he's capable of carrying up to three people. Their diet is almost entirely composed of meat, and on Auldrant they're even known for eating humans. Liger cubs in particular enjoy the taste of human flesh (which carries some pretty scary connotations for what Arietta might have eaten as a child, just sayin'). They're also capable of performing fonic artes, and can shoot lightning by channeling fonons into the red, wing-like appendages on their backs. Despite his large size, Liger can run much faster than it looks like he should be able to. He's also a very apt climber, and spends much of his free-time running around on rooftops to avoid the crowds below.
Because they have so much fur in their tails, Ligers aren't fond of water. Arietta gives Liger baths regularly so he doesn't stink up the apartment, but he still doesn't like them, and the whole affair usually takes over an hour. But that just means he's nice and fluffy pretty much all the time.
He's become quite domesticated after living in a city for so long, but that doesn't mean he's not still dangerous. He has no qualms about killing humans unrelated to him, and will attack anyone who brings harm to Arietta.
‣Surrounds one target with a red-orange light that increases one target's physical attack power.
‣Blaze Emitter with a Light/Fire FOF circle: two spirals of red-orange light surround the target, increasing physical attack by 20%.
‣Creates a crystalline barrier that temporarily raises defense of the target, generally the caster or their teammates.
‣Aqua Protection with a Dark/Water FOF circle: creates a bubble of water around the target that increases their defense for a longer period of time. ("O vapors, become our shield! Aqua Protection!")
Heal (Support) - "The power to help! Soothing Light!"
‣Heals one target at a time with moderate potency.
‣Healing Wind with a Light/Wind FOF circle: wind swirls around the target, healing more across a wider range and allowing for multiple targets. ("O gentle breeze, ease our pain... Healing Wind!")
Limited (Offense) - "Hammer of light... Limited!"
‣A crest appears on the ground below the target, who is then shot by a beam of light from the sky.
‣Spark Wave with a Light/Wind FOF circle: in addition to a beam of light, a ball of electricity shoots out, sending Wind-elemental damage across a wide area. ("Hammer of Lightning, strike! Spark wave!")
Negative Gate (Offense) - "O twisted door, open wide! Negative Gate!"
‣A dark circle appears on the ground below the target and light starts to float upwards, before turning into a large ball of dark energy that shoots outward from the center.
‣Crimson Riot with a Light/Fire FOF circle: summons a fiery, pulsating ball of energy around the target. ("Flames, come forth! Crimson Riot!")
Bloody Howling (Offense) - "O hellion's roar! Bloody Howling!"
‣A large glyph opens on the ground, shooting waving beams of red and purple light that surround the enemy.
‣Creates a fully charged Dark FOF circle.
‣Maelstrom with a Dark/Water FOF circle: creates a large whirlpool of water that throws the target into the air. ("Into the depths of the blue! Maelstrom!")
Meteor Storm (Offense) - "O countless falling stars, come forth! Meteor Storm!"
‣Large, fiery meteors fall from the sky, exploding as they hit the ground.
‣Learned from Jade in early 2016.
Evil Light (Mystic Arte) - "Now I'll show you how strong I am! This is it! Evil Light!" - View Arte
‣A large glyph appears beneath her as waves of purple energy swirl around, charging up into a ball of light above her head that she then shoots directly at one target in a shimmering wave.
‣Strikes from no more than 10 ft, generally close range only, purple light prevents foe from escape.
Big Bang (Mystic Arte) - "Feel the first beats of time! Fall! Big Bang!" - View Arte
‣A glyph appears in front of her with a sharp sound, pulling the battlefield into an altered reality of a galaxy that swirls together into a single point before exploding outward, ending with visions of a starry night.
‣Strikes everything in reach, with a greater reach meaning a weaker attack. Arietta isn't strong enough to concentrate the attack to make it fatal on an average person.