A character subverts rules in a non-criminal way to obtain an unfair advantage over others with whom they are acquainted.

Notes:
The theme "criminal fraud" is to be preferred when the when the act is clearly criminal in context.

Examples:
Johnny infuriated the Swede by cheating at the card game High Five "The Blue Hotel" (1977).

References:
https://en.wikipedia.org/wiki/Cheating