Gustav Klimt, Death and Life, 1908-1915 – Regulus' shirt has the same pattern as Death's cloak, James' shirt is patterned like the background of 'Life'
It was life and death, and death was there, on the left side of the canvas, waiting eagerly to pluck any one person from the conglomeration of life and claim them as its own. – chapter 28
Mark Rothko, Untitled (Seagram Murals), 1958 – Regulus bleeding out into the background
And he remembers looking out at the thick red blood on the marble floors and nonsensically, being reminded yet again, of Rothko. – chapter 34
Ivan Konstantinovich Aivazovsky, Gathering Storm, 1899 – Regulus' socks have this pattern
'Hang painting here?' – chapter 37
and here some little details and an alternative bloody version :) look at that snake ring being handed over <33