Most Angels, and their distant cousins Faeries are actually rather quiet, pleasant folks. They spend most of their time reading usually in large trains stations. That, and taking long walks in bad neighborhoods, and war zones.
Not so they can save us. They know we're more than capable of doing that for ourselves.
They wander through our Hells so they can see 'us' as we really are. No pretense. Just raw human savagery, and cunning. They're fascinated by our ability to survive almost anything.