Hmm... I thought about The Beast before as an Essence so... Quirk suggestions of like the Disney version's temperament sometimes springing up. Or maybe prolonged periods of solitude make him act more animalistic?

As for Essence suggestions, maybe give The Rose Elf a look? Powers he could have are like maybe some plant/flower manipulation, being able to travel through them, and shrink down to be tiny. Spy on any shady nobles through them too hehe.