kagamine rin & len lovers? Twins? BFFs? or just look alikes?

Kagamine Rin and Len are a vocaloid or vocaloids. They appear to be as twins even thought they are commonly compared as lovers or twins and lovers. Ussally in america they are twins or products are sold that "refer" them as twins. I ussally think them as twins or lovers or both because of servent of evil. They would be a cute couple? No? Well, lots of people see them as lovers or/and "mirror images". There are some products I found of kagamine rin and len, if you are an otaku fan then you would be intrested. Like on ebay.com they have a kagaminerin/len hugging pillow.

I want to know your opion?? Lovers or twins or mirror images or all 3?