Minor example. In the end of the film after The Purge has finished, Mary asked the homeless man if he will be okay. The man nods, Mary thanks him, and the man leaves the Sandin house.
Considering the man has saved Mary and her children's lives in the nick of time, it is understandable. Also, the man more or less considers the family as his savior, for not only allowing him to hide in the house (well, at least Charlie shows him his secret hideout at one point) but also Zoey killing the gang's leader who tried to kill the homeless man.
Anarchy has Leo save two women from being gunned down, gives them and another couple guns to defend themselves, and soon after allows all four survivors to tag along with him to a safe house. Sure, he has conditions, but it's obvious he's a good person.
There's also the father/grandfather of the two women allowing himself to be "martyred" so they can have enough money to live on and protect themselves against future purges. Doubles as a tearjerker.
Leo forgives and spares the life of the man who killed his son. This saves his own life not two minutes later.
It's implied at the end of Anarchy that Leo, Cali and Eva are something like Fire-Forged Friends after all they've been through together.