Leo

When Takuto was killed during the revolt at Zhoushen and subsequently revived, it was at first assumed that Takuto had been reborn with his memories locked away. In reality, due to Aion's sacrifice and the addition of half of his soul to Takuto's, a composite personality was made from the two of them. Leo contains both Aion and Takuto's powers to some extent, though only his high affinity for Esper Magic is visible right now. Because of the way Crysta cared for him while he was controlling Takuto's reborn body, he came to love her dearly, alongside Rose as well thanks to her storytelling skills.

When Crysta was taken into Takuto's dreamscape by Drepa in order to help him master his Future Sight skills so he could become an adult again, it was discovered that Leo, who was initially believed to simply be Baby Takuto, became sealed away in Takuto's mind after Takuto regained his memories at Lovcore. Having little else but Aion as company, Leo had been inconsolable until Drepa awakened him and he saw Crysta again. Deemed as a 'remnant' that would be absorbed (alongside Aion) once Takuto mastered his Future Sight skill, Leo was very relieved and incredibly happy when Crysta rebirthed him into the physical realm and took him as her child again. As a result, there's hardly ever a moment where Leo can't be found squished between Crysta's breasts, or just close to her in general. He does have an adventurous streak though.

After he was reborn, Takuto and Atria both recognized him as his own separate person. While his family line might become confusing later on, Leo is happy having a family around, especially a mother and father figure (which Takuto himself has lacked in terms of consistency).

When Legada was born to Crysta and Takuto, Leo became very close to her and even gave her a Mark. He seems very calm and soothing around her presence, and can often be found grooming her to help her relax. He has a very strong brotherly instinct, at the least. His affinities are the exact opposite of Takuto's, meaning he has a high affinity for Light and healing magicks (as opposed to Takuto's high affinity for Dark and damaging techniques). As a result, Leo might become an effective healer and supporting unit if he's trained right. He has a very high gift for magic, however, meaning he could also be an excellent mage if he's trained for it.

Leo seems destined to have amber eyes when he's older.

Recently, Leo had a Seed which resulted in a runt by the name of Glidea. She possesses bright golden eyes and light brown fur, and seems quite different than the usual demons that've come from Crysta's family before. It'll be quite some time before they find out anything about her powers though.

After being terrified by Dimenda's rage at his father, as well as the way Crysta behaved and having witnessed the death of his siblings, Leo ran away from Crysta's suite and was picked up by Immunità, who soothed the poor child and brought him to Chii once he was calmed down. While he's still prone to momentary lapses due to his trauma, it seems Leo will be able to recover if given constant care and reassurance, which Chii and Takuto are more than willing to give to him.

A reference of Leo as a baby.