There is rarely one right answer. Here are several categories of pairing options, each with a reason it may work.
Medium Purple
Similar lightness for a subtle, tone-on-tone pairing with minimal contrast.
Fuchsia
Similar lightness for a subtle, tone-on-tone pairing with minimal contrast.
Slate Blue
Similar lightness for a subtle, tone-on-tone pairing with minimal contrast.
Dark Orchid
Similar lightness for a subtle, tone-on-tone pairing with minimal contrast.
Payne's Grey
Enough lightness contrast to read as two distinct colours without feeling harsh.
Plum
Enough lightness contrast to read as two distinct colours without feeling harsh.
Mauve
Enough lightness contrast to read as two distinct colours without feeling harsh.
Sapphire
Enough lightness contrast to read as two distinct colours without feeling harsh.
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.
Silver
A low-chroma neutral lets the original colour stay the visual focus.
Lavender
A low-chroma neutral lets the original colour stay the visual focus.
Chartreuse
A saturated accent from a different hue family for a deliberate pop of contrast.
Yellow
A saturated accent from a different hue family for a deliberate pop of contrast.
Yellow-Green
A saturated accent from a different hue family for a deliberate pop of contrast.
Peridot
A saturated accent from a different hue family for a deliberate pop of contrast.