Fetish

A Fetish was a strong, usually sexual, affinity for something.

Bernice Summerfield believed Ovmakh had a fetish for military hardware, which she collected. (PROSE: Mentioning the War)

The Tenth Doctor, upon observing that Slabs were made up of solid leather all the way through, jokingly proclaimed that "somebody has got one hell of a fetish". (TV: Smith and Jones)

Ram Singh believed Matteusz Andrzejewski was into Charlie Smih because he had a "weird sexual fetish" for aliens. (TV: Detained)