What does petey say is the key to breaking through the infection the zombies become human again, aside from music?

""Well, music. I've tried classical, country, rap--it all worked, but I'm partial to bluegrass. It confuses  them and eventually breaks through the infection. But it's not enough just to blare music at 'em. You  need to engage, talk to them. The more you can make them realize you're a person, the better they'll  remember that they are, too."

Explanation:

In the seventh series of "The End of the Road," "The Run Series" by  Lynne Stahl, Jeremiah starts talking to Anna, who has become a zombie. By talking to her Anna is transformed back into human. From this incident Petey gets to know that they can help zombie become back to human not only just by playing the music but also by "engaging with them in talk" and "making them realize that they are humans too." This was the key that Petey says to break through the infection.

sonnet 130 follows the typical rhyme scheme of the form abab cdcd efef gg and is composed in iambic pentameter,a type of a poetic metre based on five pairs of metrically weak/strong syllabic positions.the first line exemplifies iambic pentameter.