Fairy does ×½ to Fire

Generations VI to IX, single types. The other way round, Fire against Fairy, is ×1.

64 Fairy and 81 Fire species among the 1025 this site covers.

Attacker, Psychic and Fairy Hatterene sprite

damage×½Generations VI to IX

Defender, Fire and Flying Ho-Oh sprite

Ho-Oh #0250

Fairy did not exist in Generation I and Generations II to V, so Fairy against Fire has no value there.

Strongest Fairy attackers

Hatterene leads Fairy at Sp. Atk 136

Sturdiest Fire defenders

Dual types that change the answer