During the apocalypse, Glenn goes back and forth to Atlanta to gather supplies. He knows his way around town extremely well because he used to be a pizza delivery boy. On one of his trips, he sees Rick being attacked by walkers, and saves him.

The Walking Dead Quotes

You can breathe. You can blink. You can cry. Hell, they're all gonna be doing that.

Negan

Was there ever a time you weren't the boss of me?

Tyreese