One True Pairing is a couple so perfect for each other. For examplethe line that Klaus ended all ships. "He's your first love, I intend to be your last. However, long it takes."
A Peiling is a kind person who would offer help and support to their friends and family selflessly. She is sometimes completely clueless to the going-ons around her, which only adds to her cuteness. She is honest to a fault and steadfast in her beliefs. Her hardworking nature makes her a brilliant teammate.
A romantic pairing (whether it be from a video game, movie, book, etc) that is completely implausible and/or bizarre, but people support it anyway, for laughs or otherwise.