"Underworld: Evolution" (2006)

They kissed once in Underworld, but in Underworld: Evolution they kissed AND had sex.

Rise of the Lycans.

No one knows this. The first film was written as a stand alone. It was successful so they continued writing sequels.

They will probably continue making more so long as the franchise is making money.

That's how most b grade movies work, if you look at franchises like Friday the 13th or Nightmare on Elm Street; these movies were not written with the intent of making dozens more. They just make one movie and if it does well they keep inventing more.

First was Underworld, Then Underworld Evolution , and finally Underworld: Rise of the Lycans but in cronological order it goes Underworld: Rise of the Lycans, Underworld and then Underworld Evolution