It is, indeed, the young summoner, a boy about the same age as Azym's standing in the middle of a small group of people when he and the priest return to the temple's main chamber. He seems to have come from the imposing double doors atop the imposing stairs, confirming Azym's guess that that's where the chamber of the fayth would be, and he looks...
...happy.
He's trying to not let his exhaustion show, but the way he's leaning on a tall blue humanoid lion-person for support reveals it anyway. To his other side is a black-haired woman wearing a fluffy black dress that not only defies gravity but also any conventional wisdom about the number of belts people are meant to wear, or what they're meant to be attached to. They hadn't been in the room before, so probably they were with Zei while he prayed or whatever it is they do.
Zei himself seems to break the convention of dress of the priests Azym's seen in the temple—although it's not like anyone had said the long body-covering robes with strange symbols were an actual uniform or anything—but he nevertheless seems to follow a similar fashion tradition, if much more elaborate and ceremonial-looking. His arms are covered from the biceps down by an intricate spiralling armwrap that ends in half gloves encrusted with small gems, and his legs and feet are adorned by sandals in a similar style. He's wearing a white and dark blue skirt that goes almost all the way to his knees, and his torso is bare except for a series of silver necklaces that grow in diameter until the largest one reaches the middle of his chest. He also seems to be wearing a cloth harness of some sort with a long metal staff attached to its back, a staff that somehow communicates both "weapon" and "ceremonial tool".
The boy seems to be in the middle of being congratulated by everyone, and while it's clear (at least to Azym) that he'd much rather take a minute or two to himself he's weathering the attention with dignity. His gaze moves over to Azym and Kahli when he hears the steps, and it stops on Azym for long enough to register the confusion at the new face before returning to the well-wishers.