Yes, I really did want to sit down and think about this for ages before I had even decided whether or not I even wanted in on the potential plot or not, thus proving ultimately that I have no life and am a total dork. Further proven by the fact that I enjoyed it. So, here you go: Shin Megami Tensei: Persona 3/Persona 4 applied to Nill in terms of Arcana, Shadow and Persona.
Nill is of the Arcana no. XVII, The Star; The Star in a positive aspect represents hope, generosity, serenity and all that good stuff. It is a good card to get in a time of crisis, but it is not a strong card; it is not enough to support, only to renew hope and allow the Journey to continue. Still, it's an excellent omen, and predicts entirely wonderful things.
Negatively, The Star represents self-doubt, a lack of trust, cynicism and pessimism
Nill's Shadow wouldn't be the particularly strong type, both in attacks or defence; she'd be quite mid-level in strength, or maybe even a bit weak. However, what would make up for that would be an unusually high Evasion rate -- so she's not a strong Shadow, but she's one of those kinds that is a royal pain in the ass to beat. An Analysis would tell you something like this:
Resist: None
Block: Ice
Absorb: Wind
Reflect: None
Weak: Pierce, Slash, Strike
Which does indeed make her sound like an easy Shadow to defeat, but then there is the addition of her skills:
Bufula
Mabufula
Garula
Magarula
Sexy Dance
Dodge Slash
Dodge Pierce
Dodge Strike
So, on top of her Evasion being an abnormally high level, it is doubled against Slash, Pierce and Strike; thankfully, she does take quite a bit of damage from any of those moves when you can hit her, so it all kind of balances out. She's also incapable of using Physical attacks, and relies heavily on her magic, so that's another point you can take advantage of.
Nill's Persona is Iris, and while there is an existing Persona of her, I don't agree much with the depiction in Persona II: Eternal Punishment, so lmao have a new version of her.
Iris is the goddess of rainbows, and also the representation of messages, communication and new endeavours. She is the daughter of the sea god
Thaumas and the ocean nymph
Electra, and wife of Zephyrus, god of the west wind. Iris acts as the bridge between the gods and humanity, delivering messages from the Heavens, to the seas, to the Underworld.
She has a number of other titles, including Chrysopteron (Golden Winged), Podas ôkea (swift footed) or Podênemos ôkea (wind-swift footed). Generally, she is depicted either as a rainbow, or as a young girl with wings on her shoulders, carrying a caduceus (a winged staff, with two snakes entwined around it) and a pitcher, with which she waters the clouds with water carried up from the sea.
An Analysis would give you mostly similar results to her Shadow, but Iris is capable of Physical attacks -- her attack type is Pierce:
Resist: Pierce
Block: Ice
Absorb: Wind
Reflect: None
Weak: Slash, Strike
And her abilities would be as follows:
Mabufula
Bufudyne
Magarula
Garudyne
Marin Karin
Mediarama
Re Patra
Me Patra
... aaand I will probably add more to this when I get home from band camp. o/ ♥