See Lola/Leon page Trivia
They are often regarded as siblings by fans due to similar names, boxart logo style, release date and they are often regarded as the English Vocaloid equivalent of the Kagamine Vocaloids. At the time of their release, media coverage of them also often called them (and later Miriam) "siblings". Even those producing the studio software also often regard the pair as "siblings" or like siblings, and understand if the fandom treats them as such. Despite this it appears that the fandom commonly treats them as a couple.