Unfortunately; Fortunately

Fortunately, the ghosts came back and murdered the rats. Mwahahaha...

Unfortunately, the rats were wearing ghost-proof armor.

Fortunately, the ghosts had special ghost-proof-puncturing arrowheads to kill the rats.

Unfortunately, the rats were too fast for the arrows, and ran into the chinks of the rubble.

Fortunately there were snakes in the chinks that swallowed the evil rats.

Fortunate for who? We're getting off on a tangent here!

Unfortunately, (for the ghosts, I presume) Evil rats never die, they just become rat ghosts and continue their haunted nibbling with misty, ethereal gnawers.

Haha no idea! I'm just rolling with it...

Fortunately...the rats and ghosts were swallowed by a tornado and the people of the city were at peace again.

Alright, a tornado! Fresh beginning...

Unfortunately, Troglokan -the evil bunny-hamster-rodent-ish-thingy- struck again!

Fortunately, Troglokan - the evil bunny-hamster-rodentish-thing - was very small. About the size of a, well, rodent.

(define 'rodent-size'. Capybaras are largish animals, and they're still rodents)

Unfortunately he had a very not-small nuclear warhead and was planning to destroy the world!

(Like a domestic mouse).

Fortunately he was stuck in a cage and taken to the zoo, where he was put in a large glass tank for kids to look at. His plans were on hold.

Unfortunately, his evil capybara henchmen were going to detonate the bomb.

Fortunately, the capybaras could not detonate the bomb as they had no opposable thumbs.

Unfortunately, the capybara henchmen had other, equally deadly weapons of mass destruction.

Fortunately, there was a rainstorm and the weapons of mass destruction malfunctioned.