Most inhabitants of Irian fall into one of the following categories.
Embers
Irian is bursting with life. Songbirds, rabbits, and other creatures roam the Garden. The streets of the Amaranthine City are filled with happy people. But the Garden never has too many rabbits, and there’s no risk of the citizens of the Amaranthine City starving—or needing to go on strike to prevent it. Sometimes, if you glimpse one out of the corner of your eye, you might see them differently, as an outline of pale white light—a glowing shadow.
These are manifestations, not living creatures. Called embers, each one is linked to a spark—a tiny echo of a soul, each one tied to a living creature. Through this connection, mortals draw inspiration and hope, and remain linked to the positive energy that flows to and from all living things. An ember resembles the mortal whose spark fuels it, but it isn’t fully conscious and doesn’t have any complete memories, merely echoes of that mortal’s brightest joys, deepest hopes, and greatest deeds. There are many more sparks in Irian than there are embers at any given moment; Irian simply dips into the pool of sparks, manifesting as many embers as the scene calls for, shaping the light of each soul into something that looks like them.
Embers don’t need to eat, drink, breathe, or sleep. They follow basic scripts, but can’t improvise and don’t have much knowledge beyond what they need for their role. As a rule, embers are happy, for they don’t know any other way to be. An ember can’t be truly killed; its body dissolves, but the spark that fueled it remains safely within Irian’s deep well of light.
While adventuring in Irian, you might see an ember that resembles you—but it won’t recognize you, and might not even appear the same age. This ember is merely your light-shadow, manifested by Irian and channeling your life force. It holds the essence of your best moments and emotions, the light within you that drives you to goodness—but merely as a spark, not the fire of a living creature.
Lumi
When a mortal dies and their soul goes to Dolurrh, the thread connecting them to Irian is severed. Any ember fueled by their spark dissolves and the spark—the essence of the hopes and brightest moments of the mortal’s life—begins to fade. But the sparks of the dead can merge together before they’re lost completely, creating a new, unique entity—a lumi, formed from the same positive energy as the embers, but possessing true consciousness and life. Unlike the embers, who aren’t fully conscious or aware of the memories they hold, lumi are sentient creatures, each with a unique identity, though their sparks give them fragments of many mortal lives. So adventurers may meet a lumi who recognizes them, and who has a few memories and traits of a fallen friend.
Lumi appear to be formed from solidified light, and generally take a body shape similar to the strongest of the sparks that formed them—usually those of sentient creatures. Their most distinctive feature is their head—a sphere of light suspended a few inches above their torso. Normally this is pure light, but with conscious effort, a lumi can sculpt and maintain a face. Their statistics can be represented by the priest in the Monster Manual (or an exceptionally powerful one might use the statistics of the war priest in Volo’s Guide to Monsters), but they don’t need to eat, drink, breathe, or sleep, they don’t age, and they’re immune to poison and disease. When a lumi reaches 0 hit points, its body dissolves and its sparks fade. If an angel of Irian is nearby, it can consume these sparks; this won’t save the lumi, but at least those memories are preserved. While most lumi are humanoids, there may be lumi formed from the sparks of other creatures, like giants or dragons, that dwell in layers of their own kind.
Lumi serve as the caretakers of the embers, and believe that by helping the embers play their roles, they’re strengthening the light in the mortals the embers are connected to. Lumi help develop and maintain the planar seeds, and some even surrender their identity in order to become new creatures within that seed; they believe that in doing this, they’re sowing the new layer with light. On rare occasions, lumi travel to other planes in service of the Architects. They are brave and compassionate, seeking always to spread hope, and ever prepared to lay down their lives for the greater good. Lumi can defend themselves, but they prefer to inspire others when possible, rather than resort to violence.
Celestials
Irian’s immortals are spirits of light and hope. Irian is noteworthy for being the home of the ki-rin. These majestic creatures often act as emissaries for the Architects. Each planar seed has a ki-rin assigned to monitor it, help the lumi, and ease transition.
Irian is also home to angels. Not as violent as the angels of Shavarath or as individualistic as the angels of Syrania, the angels of Irian embody the general principles of hope and compassion. Irian devas assist the lumi and help sustain the different layers; they are the knights and scholars of the Amaranthine City. Devas often change their form to play multiple roles within a layer, and adventurers may think that they’ve encountered multiple people, when in fact it’s a single deva. Meanwhile, planetars act as champions and ministers, and each of the Architects has a single solar that serves as its right hand.
The angels of Irian have wings formed of light, which they can conceal if they wish. In their true form, they’re luminescent humanoids of indeterminate species, but can choose to appear to mortals as a generic member of the viewer’s species. Devas also possesses the ability to change into specific forms at will.
The Architects
The Architects are the most powerful spirits of Irian. Each embodies an aspect of the plane, and oversees a region within it, as discussed in the “Layers” section. They’re unique celestials with great wisdom and power, but most of their time and energy is devoted to the planar seeds—guiding the growth of the seed, smoothing over problems, and adding a few personal touches. Planar seeds emerge within an Architect’s realm, expanding until they break off and join their new planes.
The power of the Architects is largely bound to their realms. They can’t directly intervene in the Material Plane, though they can work with warlocks (as Celestial patrons) or send lumi. Often this involves the reintegration of a planar seed, or examining regions where Mabar has removed a fragment.
Lantern archon, ravid.
Manual of the Planes: Xag-ya.
Monster Manual III: Lumi.