[Update: the book is Fool's Run by Patricia McKillip!]
Dear Internet, please help me find a poorly-remembered book!
It was scifi, likely published in the 80s but conceivably late 70s or early 90s. I do not remember much of the plot but I remember that there was a playing card motif and I think also a harlequin motif.
The most distinctive feature I can remember is that there was a virtuoso pianist who would occasionally go into a fugue state; I believe he was one of the main characters.
@jwisser is it possibly Fool's Run by Patricia A. McKillip ??
@spills HOLY SHIT. This might be it! And even if it isn't, McKillip wrote Riddle-Master, one of my favorite series of all time, so this goes immediately next on my reading list either way. Thank you!
@jwisser omg amazing!!! I hope it's what you were looking for OR a fun new discovery :D
@queenofnewyork @spills Ah, I'm so glad! It was a formative series for me, and these days I stretch the time between readings as long as possible so I can savor it all over again each time.