There is rarely one right answer. Here are several categories of pairing options, each with a reason it may work.
Ash Grey
Similar lightness for a subtle, tone-on-tone pairing with minimal contrast.
Sage Green
Similar lightness for a subtle, tone-on-tone pairing with minimal contrast.
Silver
Similar lightness for a subtle, tone-on-tone pairing with minimal contrast.
Greige
Similar lightness for a subtle, tone-on-tone pairing with minimal contrast.
Verdigris
Enough lightness contrast to read as two distinct colours without feeling harsh.
Duck Egg Blue
Enough lightness contrast to read as two distinct colours without feeling harsh.
Powder Blue
Enough lightness contrast to read as two distinct colours without feeling harsh.
Storm Grey
Enough lightness contrast to read as two distinct colours without feeling harsh.
Prussian Blue
Strong lightness contrast and saturation for a bold, graphic pairing.
Tyrian Purple
Strong lightness contrast and saturation for a bold, graphic pairing.
Cinnamon
Strong lightness contrast and saturation for a bold, graphic pairing.
Burgundy
Strong lightness contrast and saturation for a bold, graphic pairing.
Ash Grey
A low-chroma neutral lets the original colour stay the visual focus.
Silver
A low-chroma neutral lets the original colour stay the visual focus.
Grey
A low-chroma neutral lets the original colour stay the visual focus.
Taupe Grey
A low-chroma neutral lets the original colour stay the visual focus.
Tyrian Purple
A saturated accent from a different hue family for a deliberate pop of contrast.
Navy Blue
A saturated accent from a different hue family for a deliberate pop of contrast.
Midnight Blue
A saturated accent from a different hue family for a deliberate pop of contrast.
Burgundy
A saturated accent from a different hue family for a deliberate pop of contrast.
Black
Meets WCAG AA contrast (8.4:1) for normal text if used as text/background.
Navy Blue
Meets WCAG AA contrast (6.4:1) for normal text if used as text/background.
Midnight Blue
Meets WCAG AA contrast (5.9:1) for normal text if used as text/background.
Prussian Blue
Meets WCAG AA contrast (5.4:1) for normal text if used as text/background.