Mark, the Prince of the North, is being subjected to a marriage contest by his overbearing parents. Jinyoung, the Prince of the South, is bribed to compete by his meddlesome sisters. When the two meet by chance before the contest's beginning, both exchange false names and false identities, leaving each other completely unaware of the other's background...and the fact that their budding attachment may have an unexpected impact on the contest's outcome. Markjin Fairytale AU!

https://www.asianfanfics.com/story/view/1345579/the-prince-and-the-pea-romance-fairytaleau-got7-jinmark-markjin-marknior

PS : this is from my fav markjin author *cry* because it's really good!!