Felix and Kiseki for the physical description ask?
I'll start with Felix since i have much more text with him. (buckle your seatbelts this might take a hot second)
Starting with two descriptions of him by Nerium in this piece, the latter of which is my personal favourite description of him! (technically he's like 13 or something in this, which is about 10 years younger than he is when the book starts, but shhhh the vibes still match)
... The boy had quite delicate, sharp, features, though they still had a soft look to them. Nerium was guessing he was somewhere in the area of thirteen. His hair was just past chin length, at an awkward length where it was just short enough to not fit properly into a ponytail or other restraint, but just long enough to get in the way, with a swooping half-fringe that draped over the right side of his forehead, almost falling into his eyes. The rich red of his tunic and tidy fit of the black undershirt were both definitely noble clothing, but there was a fairly sizable rip on the tunic’s side that had been sewn up in a distinctively inexperienced manner.
... (In the future, whenever Nerium thought back to this first meeting, this image was always the first that came to mind. Felix, grinning, eyes still sparkling with laughter and evening sun, hair almost golden in the dappled sunlight seeping through the autumn leaves above, one hand still shepherding loose hair out of his eyes and the other resting on his cane again.
Something about the picture had always felt ethereal to Nerium, and though he no longer thought of Felix as the boy from a fairy tale, some moments it seemed all too accurate.)
Veering closer into canon, here's how Helen describes Felix when she first meets him. (RIP George, whoever he was)
...she’d moved about two crates by the time she noticed an unfamiliar young man walking across the grass.
Frowning, Helen paused halfway through lifting another crate, and squinted at said young man. The first thing that caught her eye was his past-shoulder-length bright copper hair, and the second thing was how easily he was interacting with the various carnival hands he passed.
Actually, maybe that should have been the first thing she’d noticed, considering Helen had never seen him before.
Helen huffed, rolling her eyes. Good heavens, George, how many times do people have to tell you to pay attention to who’s going backstage?
Despite the fact that the ginger was definitely not a carnival member, he seemed entirely at home in the bustle of the backstage area, ducking around two brothers as they carried a heap of cables across the grass with a wink, neatly avoiding getting run over by Rosie (one of Helen’s fellow dancers, who as usual appeared to be late for something) and waving at her as she receded into the chaos.
Helen watched a moment longer, then decided he wasn’t her problem (that would be George’s problem when India found out he’d let another visitor sneak backstage, to be specific).
And last but not least, here's Scarlet's description of Felix when she first meets him, this one's getting very close to where canon starts.
Scarlet cast a glance at him out of the corner of her eye, curious.
They were about the same height, she realized with some surprise. Probably a lot closer than it actually looked- casting a glance down at Monarch’s feet- considering he appeared to be wearing platform boots.
Aside from said boots, Monarch was dressed simply in a dark blue tunic, knee-length loose black coat and black gloves with several rings. He had dark hair just past shoulder length, tied back in a ponytail, and… to Scarlet’s surprise, a pale turquoise courting necklace poking out from his tunic’s neck.
“You’re surprisingly nice.” Scarlet observed. “Also kinda short. You’re like, the same height as me.”
“Thank you,” Monarch replied, “also, rude. True, but rude.”
They continued walking for a moment, breeze ruffling the end of Monarch’s coat and snapping at the various awnings. Monarch walked quite softly, Scarlet noted, the only sound he was making was the click of his cane on the cobbles.
Canonically Felix is not exactly the same height as Scarlet; she's five-six/167 and he's five-seven/170, but he's still definitely short for a man in Solace. (average height is around five-ten/177)
other details that aren't in text or I didn't include here:
Shannon calls Felix the sun pretty often, make of that what you will.
I call Felix ethereal pretty often, make of that what you will as well.
Felix is described as moving in a feline way quite often, and I personally write him with the thought in mind that he basically never stays still.
Somehow none of these descriptions mention it, but Felix is heterochromatic; his left eye's green and his right eye's blue.
He also has burn scars on the left side of his face and neck; those ones didn't get mentioned in text because he didn't have them in the first piece, he's too far away from Helen for her to notice in the second, and he's wearing a mask that covers his face in the third.
His hair's not dark as the third piece would suggest, it's bright ginger, but when he's out as Monarch he wears a wig. His hair's still the same length though.
Felix really likes wearing eyeshadow and jewelry, but he doesn't actually do it much due to that being a distinctly Amorian preference and him spending a lot of time around Solite nobility.
He's pretty obviously of Amorian blood, significantly less so than his twin brother Shannon (who's still a ginger but it's much more diluted; also he's not heterochromatic), which can cause quite a bit of conflict due to Amorians not being very well accepted in Solace.
(technically he's half Amorian and half Solite but the second half isn't very obvious)
He wears a lot of rings and is constantly fiddling with them.
He wears pretty flashy clothes.
Now, Kiseki on the other hand, I don't actually have any in-text descriptions of him, Mercy City being a newer WIP of mine. I do, however, have his physical description in the MC character doc! (here's that)
Kiseki Terris-
Physical description- Male, 20. 5’7, lithe build with strong sleeper muscles. Suntanned freckled light skin, slanted dark brown eyes. Neck-length straight near-black dark brown hair with a sharp fringe. Nearsighted, wears glasses.
I think his glasses are the rounded-rectangular type ones, the frame's probably metal and silver.
I can't think of anything else, so thank you for the ask! Hope this wasn't too wall-of-text-y I just have a lot of thoughts on my fictional people (don't worry Kiseki's definitely going to get there as well in a bit)