Alan explains that Equanimity is similar to the Serenity prayer:

God grant me the serenity 
to accept the things I cannot change; 
courage to change the things I can;
and wisdom to know the difference.

It’s not being indifferent. You remain calm. It’s a state cooled from the flames of Samsara, imperturbable. In Theravada Buddhism is a cultivated emotion. In the Mahayana tradition is an aspiration. Don’t judge people according to their appearances, because that’s where attachment and aversion come from. Neither you analyze persons trough emptiness. You would dehumanize them. So don’t go too shallow nor too deep. Only enough until you find a being like yourself, which wants to be happy and to avoid suffering.