In comics traditionally issue #1 is the origin story, where we first get to meet our hero or heroes and learn how they become the characters we'll be following. This is the most important jumping on point, so it always bewilders me when the first issue is not used to introduce the character; it's the opposite of welcoming.
DC's big relaunch last year gave every title a new number #1, but in an absolute festival of missing the point, most writers didn't bother with an origin story. Some, notably Green Lantern, opted to ignore the entire event and continue with the story in progress from the previous series, apparently unaffected by the universe changing events that spawned the renumbering. Others commenced with a story to introduce the characters, but not an origin story.
Only a handful, and those mostly being the series that introduced entirely new characters, opened with an actual origin. And I think this may stem from DC's odd idea of taking a clean slate and then squeezing out all the possible freshness by burying it under five years of back story.
So a year later we are getting issue zero of everything. If issue #1 is traditionally the origin, then issue #0 is a tale of what happened before the hero became the hero. Of course when issue #1 opens five years into the story, then issue #0 can be any time before that. But at least in these days of glacially paced, writing for the trade decompression, the issue #0 at least tempts you with the prospect of a done in one single issue story, which is why I've taken another look at several titles I dropped early in the relaunch.
Birds of Prey actually has something closer to an origin than issue #1 had, giving us the first meeting of Black Canary, Batgirl, and Starling. And while it is a done in one, it is caked in plot hooks for other comics; the upcoming Team 7 book, the current BoP, the new slimline Amanda Waller, who I still didn't recognise without a label, and whatever book she's in now that I'm not reading. Even so, I enjoyed it enough to consider giving BoP another go, although the gratuitous underwear shot cooled my interest a little. How many issue zeros with male leads are going to show them in their boxers, I wonder?
Wonder Woman was a delight. A fun Silver Agey tale about Wonder Woman as a teen, writer Brian Azzarello having spotted that you don't need to overload the narrative with a bunch of story hooks to keep readers coming back, you just need to tell a good story.
I enjoyed half of Batman #0, with it's origin of the Bat-Signal and the effect that light in the sky has on several members, or future members of the Bat-family. Yes, it was continuity-heavy, but still a nice mood piece. The other half was a story set immediately before Bruce thought of dressing up like a bat, which featured Red Hood, who is now a gang, the leader of which has the original Silver Age Red Hood dome, but misses the point of having it completely covering his head by having it only go down to nose level. It's kinda stupid. Is it still the Joker? I don't care.
Green Lantern followed its course of ignoring the rules that everyone else has to follow by continuing the story currently in progress. This did involve giving an origin to yet another male, Earth Green Lantern (seriously, that's five now. Are women constitutionally incapable of "overcoming great fear" or are the rings just sexist?), but only because it had reached that point in the story. And issue zeros have never been associated with origin stories particularly, anyway. This is issue twelve and a half to all intents and purposes.
Supergirl was kind of the first part of the story that we met in the middle at the beginning of issue #1. It might even have been better placed as issue #1, since it introduces us to the character and gives us some background, which the actual issue #1 failed so badly at, being basically a fight scene between someone you didn't know and some other people you didn't know. If this had been issue #1 then at least you might have had some investment in one of the characters when they got to the big fight scene.