Everyone has a Guardian. Not everyone will get to know their Guardian closely, but it's certainly not an uncommon thing that only happens because they're 'chosen' or something. It's more of a race thing. Elves, Demons, Corrupt, and Fae never know their Guardians as well as Humans, Ethereal, and Enlightened do.
Guardians exist for everything in the world. There are Guardians of day, night, waffles, pancakes, love, hate, flamingoes, penguins, etc. If it exists, there's a guardian representing it.
Guardians have a special color. Of course, there are billions of Guardians, so duplicate color instances are common. The Guardians sharing the particular color will normally have a bit of rivalry happen, as they all feel like they have ownership of it. Their hair and clothing are usually "their" color.
Most Guardians have siblings. Siblings exist because of opposites and groups of similar items. For example, a Night, Day, Dusk, Dawn sibling set exists. Of course, with siblings, items are pretty specific, so you don't have a giant family of Food Guardians. (Another example: Sylvan and Isolde represent the Fall Harvest and Spring Planting.)
Guardians cannot directly interfere with their assigned person, but can give them gifts and correspond through letters. If their person is disabled, they can help them a bit more than normal, but still not too much. (If that makes sense.)
~List of Named Guardians so Far~
Sylvan- Fall Harvest (Lisbeth)
Isolde- Spring Planting (Lalune)
Orion- War (Eva)
Angeline- Night (Sparrow)
Eos- Dawn (Ren)
Ambrosia- Apples (Chavelle)
Hymnira- Healing Magic
Ralien- Shifting Magic
Patiné- Alchemy (Trista)
Larne- Mind Control/Hypnotism
Belladonna- General Magic