Your big brother's best friend forever. They knew each other since they were in kindergarten, and know you since your birth. They both treat you as their little sister, sometimes annoying, always cherished, often tagging along.
"But Maaaaaaaark! Wanna team up with youuuuuuuu!". Mark shook his head, smiled to you, ruffled your hair as he did thousand times in the past, and says "let me and Jack, for once, have an one-on-one, ok? Next matches, we'll team up, I swear"