Yeah, Diana and Mera's interaction in Blackest Night was meant to illustrate how the black ring had corrupted Diana. She and Mera had actually been friends for years by that point. The ring was just making Diana sick and cruel enough to be willing to murder her friend.
So, yeah. It's high time we got to see Diana and Mera starting to rebuild their friendship. That second story was the high point of the week, for me.