People who would be besties (and yes, I mean besties, not married xD)

Natasha Romanoff and Tauriel

Harry Potter and Percy Jackson

Loki and Thranduil.....would have a love-hate thing going on

Gandalf and Dumbledore

Bilbo and John Watson (Hmmm, I wonder why?)

Sherlock and nobody because only John xD

Sauron and Voldemort 

Aragon and Prince Caspian (from the amazing MadiB79)

Nazgûl and Death Eaters....would also have a love-hate relationship (from the fabulous MadiB79)

Hermionie and Eowyn (from ellethwen Vanadesse_Undomiel)

Ron and Sam (from the awesome Willow_Rosenburg)

.....can't think of anymore, but I would watch any of these as movies ehehehe xD