There is rarely one right answer. Here are several categories of pairing options, each with a reason it may work.
Cadmium Red
Similar lightness for a subtle, tone-on-tone pairing with minimal contrast.
Crimson
Similar lightness for a subtle, tone-on-tone pairing with minimal contrast.
Cherry Red
Similar lightness for a subtle, tone-on-tone pairing with minimal contrast.
Vermilion
Similar lightness for a subtle, tone-on-tone pairing with minimal contrast.
Carmine
Enough lightness contrast to read as two distinct colours without feeling harsh.
Salmon
Enough lightness contrast to read as two distinct colours without feeling harsh.
Light Coral
Enough lightness contrast to read as two distinct colours without feeling harsh.
Maroon
Enough lightness contrast to read as two distinct colours without feeling harsh.
Black
Strong lightness contrast and saturation for a bold, graphic pairing.
White
Strong lightness contrast and saturation for a bold, graphic pairing.
Mint Cream
Strong lightness contrast and saturation for a bold, graphic pairing.
Off-White
Strong lightness contrast and saturation for a bold, graphic pairing.
Taupe Grey
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.
Graphite
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.
Lime
A saturated accent from a different hue family for a deliberate pop of contrast.
Spring Green
A saturated accent from a different hue family for a deliberate pop of contrast.
Chartreuse
A saturated accent from a different hue family for a deliberate pop of contrast.
Lime Green
A saturated accent from a different hue family for a deliberate pop of contrast.