In <em>Inferno</em>, Dante describes how he ended up visiting Hell. He tells us that when he was thirty-five (considered the midpoint in his life), he found himself lost in a dark wood. He was lost because he was astray from the "right way" (the path to salvation). When he attempted to climb a small hill, he was not allowed to pass, as this hill was guarded by three "beasts": a leopard, a lion and a wolf. These animals are considered to represent the three main divisions of sin: incontinence, violence and malice.
Ponyboy picks up the glass because he feels bad about breaking it. It's strange considering his previous actions. This action is a relief to Two-Bit because it shows that Ponyboy isn't completely hardened.