My New 52 History. Because I like be imaginitve! Know it's not the best, but it's OK. Sorry if it's confusing.
So the superhero thing in the DCU begins in a 9 time span with Batman has been operating along with his young 11 year old ward, Dick Grayson as Robin. However little have been known about them except tales told by the insane criminal, the Joker, so they have been a urban legend. 3 years go by and Superman is the first publicly known superhero. This leads to Wonder Woman, The Flash, Green Lantern, Aquaman, and Martian Manhunter come out of hiding and on to the superhero scene. This also leads to superhero watches going off in Gotham City in which Batman and Robin are spotted and become known. Only to increase the amount of notrious villains to make their way to Gotham to take on the Bat, match wits with him, or just get a laugh.
Batman and Robin being spotted for the first time.
Within the next year trouble comes up! And this means a threat to the world kinda thing. Superman, Batman, Wonder Woman, The Flash, Green Lantern, Aquaman, and new comer Cyborg join together to stop this vistor Darkseid and his forces. Heroes Robin and Martian Manhunter does not take part as Robin was told to stay in the Bat Cave and help give newcomer, Barabra Gordon training to become Batgirl. While Martian Manhunter decides to take a less social way of handling the invasion by defending Earth solo. After the events the Justice League is formed. After the formation of the Justice League the hero named Batgirl makes her debut followed by heroes Green Arrow, Black Canary, Hawkman, The Atom, and others. It should also be noted during this time the team Young Justice is formed consisting of Robin, Donna Troy, Speedy, Starfire, Beast Boy, Raven, and Cyborg whom went out of the League for awhile to help this team. Martian Manhunter took Cyborg's place (this could mean the mention of MMH being int he League in the past). Within the next year Superman incounters Supergirl for the first time.
Within the next 2 years of the JL forming, Dick leaves the Batcave and Barbara left her mantle of Batgirl. During this time Batman had taken in Jason Todd (who got shot down with a couple of being Robin) During this time Dick has become Nightwing, Babs had got shot by the Joker, and Superman got killed by Doomsday. Within the next months. Tim Drake finds out the idenity of Batman and Robin (Dick Grayson) and takes on the mantle of Red Robin (as he was afraid of hurting the Robin legacy. Remember that was Tim's fear when he became Robin). Also during this time Superman has comeback to life. This all takes place within 3 years of the JL forming.
In the middle of 4th year, Batman dies and Dick takes on the mantle of Batman and gives the mantle of Robin to Bruce's biological son from Tailia (the daughter of one B-Man and Dick's earliest foes) the mantle of Robin in which Tim leaves to search for Bruce. When we walk into the New 52 books that do not take place within the past (Action Comics and JL), it is right when Bruce is becoming Batman once more. Tim Drake also gathers a group of teenage heroes becoming the Teen Titans leading to the start of the New 52.