Learn Italian: L'eroe mortale nacque e decise la sua vendetta. - The mortal hero was born and decided his revenge.

Nacque is the passato remoto (historical past) of the verb nascere (to be born) in the third-person singular. While English uses the passive voice ("was born"), Italian uses this active verb to express the exact same idea.

Is there a trick to remembering the passato remoto form decise?

Yes! Decise comes from decidere (to decide). Many verbs ending in -dere follow a specific irregular pattern in the passato remoto where the -d- changes to -s- for the io, lui/lei, and loro forms. This gives us io decisi, lui decise, and loro decisero.

Is eroe masculine or feminine, and how can we tell here?

Eroe (hero) is masculine. Because it starts with a vowel, it takes the article l' (short for lo). The adjective mortale ends in -e, meaning it can be either masculine or feminine, so it doesn't give the gender away. If the hero were a woman, the word would be l'eroina (the heroine).

Why is there a la before sua vendetta if it just means "his revenge"?