The CW's new superhero action/drama series The Flash has been the hit of the season so far, and it's only halfway done.  There have been so many villains, Easter eggs, and plot moments pulled straight from the comics that you easily could have missed a few.  So whether you're new to the show and want to get caught up, or just want a refresher before it returns Tuesday night, we've put together a list of ten items of importance.

Hit the jump for everything you need to know about The Flash.

Who is The Flash?

Mild-mannered Central City forensic tech Barry Allen (Grant Gustin) was introduced to The CW viewers by way of the Arrow season two episode, "The Scientist."  He used his scientific expertise to help out Oliver & Co. before heading back to Central City at the worst possible time.  While going over his notes pertaining to his mother's murder (a cold case from his childhood that forever changed his life), a raging thunderstorm assaults the city.  At the same time, S.T.A.R. Labs fires up their particle accelerator for its inaugural run; things don't go as planned.  A massive explosion radiates across the city and Barry is caught in its wake.  He watches the crime lab around him being demolished in slow motion just before he's struck by a bolt of lightning, sending him into a coma.

Nine months later, Barry wakes up to find that he's on a new show he's developed incredible super speed in addition to a rapid healing ability.  While his powers are still in their infancy, Barry quickly learns he must balance his new responsibilities as superhero, crime-fighter, and science experiment against his more down-to-Earth day job while keeping his new identity a secret (for the most part).  And though he gets his super-suit in relative short order thanks to the folks at S.T.A.R. Labs, he doesn't get his famous moniker until a few episodes later.

What exactly is S.T.A.R. Labs?

Other than being at the heart of The Flash's creation (and that of all of the other new superpowered folk dubbed "metahumans"), S.T.A.R. Labs was one of Central City's leading scientific research facilities.  Though the initial goal of studying sub-atomic particle collisions is now a bust, what with the collider having been destroyed, the team can now focus all their efforts on figuring out just what makes Barry tick.  In addition to helping Barry figure out his powers, they also do their best to keep him alive in his fights against other metahumans by deducing their weaknesses.  Once it becomes apparent that there are quite a few dangerous metahumans out there, S.T.A.R. Labs becomes a sort of holding pen for those that Barry defeats.

Who are Barry's allies?

First up are the S.T.A.R. Labs scientists Caitlin Snow (Danielle Panabaker) and Cisco Ramon (Carlos Valdes), who share names with other DC Comics characters (though it remains unclear whether or not there are plans for them to take on their comicbook counterparts' powers).  Caitlin is an expert in the field of bioengineering and helps to discern Barry's abilities, and those of the other metahumans, on a molecular level.  She also happened to be engaged to the facility's structural engineer, Ronnie Raymond (Robbie Amell), who was presumably killed during the accelerator's explosion when he sacrificed himself to save the others.  Cisco is a brilliant mechanical engineer who brings a youthful energy and humor to the team, along with expertise in weapons and other devices, like Barry's heat-proof crime-fighting uniform that was originally designed for firefighters.

Outside of S.T.A.R. Labs, Barry's allies include members of the Central City Police Force Detective Eddie Thawne (Rick Cosnett) and Detective Joe West (Jesse L. Martin).  The former is a tenuous ally at best, since Thawne works alongside Barry, but sees The Flash as a menace to the city.  West, on the other hand, is essentially Barry's second father, having adopted him after Barry's mother was murdered and his real father was sent to prison for the crime. West is one of the few who knows Barry's secret identity and tries to help keep him safe while encouraging him to fight crime at the same time.  Also helping Barry out in his endeavors is the Starling City crimefighting team, led by the hooded vigilante, Arrow.

Wait, I thought this was The Flash.  Why are the Arrow characters showing up?

Not only do The Flash and Arrow exist together on The CW and in the DC Comics, the characters and events occupy the same fictional world.  This lets members of each team cross over into each other's stories, best exemplified so far in the cross-over episodes "Flash vs Arrow" and "The Brave and the Bold."  This storytelling tactic doubles the size of the world and exponentially increases potential plots.  It also introduces the possibility of a mini, television-based assembly of the Justice League, well before the superhero team makes its way to the big screen.  Plus, Felicity Smoak (Emily Bett Rickards) gets some extra screentime, which never hurts.

It seems like there are some romantic entanglements going on.

Ah, so remember that The Flash airs on The CW, and while the superheroic action elements are excellent, there's a heavy emphasis on character relationships, especially romantic ones.  With Barry at the center of multiple love triangles, The Flash has plenty of opportunity to explore these.  First up is Iris West (Candice Patton), the daughter of Joe West and best friend/adopted sister to Barry himself.  Barry struggles with his affection for Iris, even admitting his feelings for her at one point.  The trouble is that Iris only seems to see Barry as a friend, further complicated by her ongoing relationship with Eddie Thawne, and her relatively new obsession with The Flash himself.  Barry has a tough time separating his costumed personality from his true identity when it comes to Iris, which is a recipe for relationship disaster, ie good CW drama.

Barry has also dabbled in a bit of intercity romance, having flirted quite a bit with Team Arrow's Felicity.  You'd think the two would have hit it off: both of them have brains, Felicity has a mask fetish, and Barry has a thing for damsels in distress.  But they gave it a shot and it ended in an awkward but amicable friendship.  I'm still pulling for Barry and Caitlin, but the reappearance of Ronnie Raymond might complicate that a bit further.

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Who are his enemies?

This is where The Flash really has fun with its DC roots.  Taking a page from its brother-series Arrow, The Flash wastes little time in rolling in infamous Flash villains from its comicbook pages.  The pilot starts the trend by introducing the bank-robbing metahuman Clyde Wardon, aka the Weather Wizard.  Each episode thereafter follows with a Villain of the Week, burning through Flash's antagonists by the hour.  We've seen one-man-army Danton Black/Multiplex, uncouth businessman Simon Stagg, the poisonous Kyle Nimbus/Mist, the cold-gun-wielding Leonard Snart/Captain Cold, the explosive Bette Sans Souci/Plastique, General Wade Eiling, Tony Woodward/Girder, Farooq Gibran/Blackout, Roy Bivolo/Prism (or Chroma, or Rainbow Raider), and the mysterious Man in the Yellow Suit, aka Reverse Flash.

Pretty intense list, right?  Barry has managed to defeat most of his villains within their allotted hour, with some of them dying, others landing in prison, and still more escaping to return another day.  Other infamous members of the rogues gallery have been teased, so there are plenty more to come, but The Flash will have his hands full if this keeps up, even if it's a comicbook fan's dream come true.

Who are his mentors?

Let's keep in mind that Barry's a fairly young guy who has been blessed/cursed with incredible abilities and tasked with a responsibility to put all the villainous metahumans down.  With that kind of pressure, it'd be easy for anyone to go off the rails or turn to a life of crime.  Luckily, Barry has a few older and wiser mentors in his life who are helping to guide him.  First and foremost is his adopted father Joe West, who also happens to be his superior at the police department.  Joe has known that Barry was The Flash pretty much from the getgo and does his best to keep his son safe while acknowledging that his abilities are the only weapon they have against the other metahumans.  Some of the show's best character moments occur between this father/son duo, who have a very complicated relationship to say the least.

Speaking of complicated, Barry's workplace mentor Dr. Harrison Wells (Tom Cavanagh) may just be the show's most interesting character.  That's saying a lot.  Wells is a brilliant scientist who arrived in Central City to fund and oversee the particle accelerator, and apparently became paralyzed from the waist down due to its explosion.  Turns out, this isn't exactly true as Wells is shown (to the audience only) to be quite whole ... and possibly a time traveler.  On one hand, Wells uses his expertise and intelligence to help Barry overcome his limitations while simultaneously using the speedster's abilities to further his own research.  But there's a more sinister motive to Wells' behavior...

As a side note, Barry's real father is still very much in the mix as a mentor to his son, though he's locked up in prison at the moment.

So that guy in prison is Barry's dad? Why does he look so familiar...

Well, if you watched the 90s adaptation of The Flash, you might recognize that show's title character as played by John Wesley Shipp.  He returns for the new version as Barry's dad, Henry Allen.  Shipp's is not the only appearance that's a throwback to the old TV show, as actor Amanda Pays also showed up recently as Dr. Tina McGee, a role she played in the original series.  A pretty nice nod to the first series and a fun addition for fans.

Any other Easter eggs we should know about?

While a lot of these may simply be Easter eggs to give fans a little thrill, some of them will certainly pay off in future episodes/seasons.  For example, Flash tests his abilities at a Ferris Air facility, a name tied heavily into Green Lantern and Star Sapphire lore.  Does that mean the mini-Justice League will rope those characters in?  Who knows?  There are also references to other heroic characters through nods to Wayne Tech, Jonah Hex, Metamorpho, and Captain Atom, just to name a few.

And there are plot arc references to "Flash: Rebirth" and "Crisis on Infinite Earths." Oh, and then there are other potential villains like Gorilla Grodd (who is name dropped multiple times, even showing the research specimen's busted cage), Killer Frost, Black Adam, Heatwave, and Reverse-Flash and/or Professor Zoom.

So what's the deal with the Man in the Yellow Suit?

From the outset, Barry has been chasing after the Man in the Yellow Suit, a lightning-fast blur that was somehow responsible for his mother's death when he was a child.  He's spent his life trying to track the man down, and now that he's developed superhuman abilities of his own, Barry finally has a real shot at getting justice for his mother's death and his father's wrongful imprisonment.  The thing is, the answer to that mystery was right under Barry's nose from the moment he started working with the S.T.A.R. Labs team.

I mentioned that Dr. Wells did not have only the best intentions for Barry, but rather some ulterior motives.  It's still not entirely clear just what Wells' plan is for the speedster.  What we do know is that he has a highly advanced AI system with access to news headlines from the future, and an obsessive drive to help bring Barry along a specific path.  It was also revealed in the mid-season finale that, after Barry's ill-fated first fight against the Man in the Yellow Suit aka Reverse Flash, Wells was in possession of the titular suit, complete with an experimental tachyon device that grants the wearer superluminal speeds.  Wells is also shown wearing a ring decorated with a lightning bolt, which Flash comic fans will recognize as being similar to the one the Flash uses to house a super-compacted costume.  So what does it all mean?

Well there are plenty of theories going around the internet about just that.  The easy answer is that Wells is actually a villainous time-traveling speedster bent on ruining Barry Allen's life and using him for his own means.  Other folks think that Wells is actually somehow related to Eddie Thawne, perhaps the future-born time-traveler named Eobard Thawne, aka Professor Zoom, aka Reverse-Flash.  It would explain why the Man in the Yellow Suit had a perfect opportunity to off Thawne, but went out of his way to leave him be.  Whatever the true nature behind Wells' actions and the motives of the Man in the Yellow Suit, the fact is that the current Flash is literally not up to speed with him.  It will take the second half of The Flash's excellent first season to answer some more questions and give Barry a chance to battle with his nemesis once again.

The Flash returns to The CW Tuesday, January 20th at 8pm.