I love the name choice for Demyan. In fact, it is an old russian name, which became very rare in the urban areas in the 20th century. It gives a nice “ancient” vibe to the character, which is quite fitting, considering who he is :))) And it’s funny, the parallel with “demon” did not occur to me either, but I say it’s a bonus! :D
Demyan definitely already commands attention and I already have a thing for him because of that particular description of how light always evades him. It is a very compelling theme.