incidental expense, incident, unessential, nonessential, inessential, parenthetical, accompanying, concomitant, secondary, related, more...

intentional, deliberate, planned, premeditated

plot, character, setting, theme, tone, style, point of view, more...

mere, many, other, little, nice, such, first, best, latter, new, central

casualty unrelated,   for background,   not the main action,   by blows,   side factor