The Arrowverse has a lengthy history of teasing storylines early on, only to dangle them, saving said stories for future arcs. A couple of notable examples include Oliver unwittingly crossing paths with his son’s mother in The Flash episode of the Arrowverse’s first crossover and Gorilla Grodd’s arrival in Gorilla City during The Flash’s sophomore effort. Meanwhile, a recent instance can be found in the introduction of Vigilante in Arrow season five, but the nature of the character’s identity being withheld until early in the show’s sixth run.

Of course, there are a several examples where the slow reveal works flawlessly and many others that fail to deliver on what seemed to have been promised. Still, within the Arrowverse are a few dangling pieces that have yet to be addressed, such as Barry’s creation of Gideon or finite details concerning Superman’s history with General Zod. These bits of information are to hopefully be explored at a later date. However, many of the mysteries that have debuted during the current seasons of Arrow, The Flash, Supergirl and Legends of Tomorrow will need to be solved sooner rather than later, preferably sooner. Here are 15 burning questions we hope the Arrowverse will answer before the shows conclude in their respective season finales.

15 TALIA AL GHUL'S FATE

Lexa Doig as Talia al Ghul on Arrow

Arrow’s fifth season closed on the show’s -- and probably the Arrowverse’s,-- biggest cliffhanger yet: Lian Yu was destroyed with a majority of Oliver’s extended family trapped on it. At this point in season six, we know of only a few casualties: Malcolm Merlyn (who sacrificed himself to save Thea before the explosion), the mother of Oliver’s son, Samantha Clayton, and presumably Digger Harkness/Captain Boomerang and Evelyn Sharp. While the aftermath of the events on Lian Yu are still prevalent with Diggle, William, and Thea, everyone else seems relatively unscathed.

However, the status of one person in particular is curiously unknown. Nyssa al Ghul made it out alive, according to Slade, but her sister Talia’s fate remains a mystery. At present, there’s no reason to believe she didn’t survive, but confirmation would be nice, especially if her return begets an enthralling story.

14 BARRY'S SYMBOLS

Barry's Symbols in The Flash Season 4

One of the earlier mysteries in The Flash’s fourth season relates to the odd sequence of symbols Barry draws upon his return from the Speed Force. Initially scrawled across the walls of a room in CCPD, the then confused Speedster subsequently scribbles them in one of the Pipeline’s cells. Cisco soon discovers the code translates to “This House is Bitchin’,” but even that offers few clues. When questioned, Barry asserts he has no knowledge of the symbols himself.

Of late, The Flash has ceased focusing attention on the symbols. Fans haven’t forgotten, though; surely Barry’s writings bear importance that will hopefully receive exposition later this season. Some theories suggest they allude to a speed formula. Others posit that they’re somehow intrinsically tied to whatever The Thinker’s planning, perhaps an answer to a puzzle yet to be broached -- one that could aid Team Flash in defeating this season’s big bad.

13 MORGAN EDGE'S MOTIVES

Adrian Pasdar as Supergirl's Morgan Edge

Often a background player in larger Superman stories, Morgan Edge comes to the fore every now and again as the leader of Intergang and a media mogul. Intergang, teased in Supergirl season two thanks to John Corben’s reported connection, typically has ties to Darkseid; given the story presumably being told in the DCEU, it’s difficult to say whether the Arrowverse’s crime syndicate will receive similar development. The most important question, however, concerns Morgan Edge’s intentions as we head into the back half of Supergirl’s third run.

Thus far, we’ve seen him attempt to turn public favor away from both the Girl of Steel and Lena Luthor. The latter has especially triggered Edge’s artful machinations, as he’s tried killing her at least once. His motives and whether this version of the character is the head of Intergang are but two enigmas the show should explain by season’s end.

12 THE REVEAL OF MALLUS

Legends of Tomorrow poster

Going into to both seasons one and two of Legends of Tomorrow, there’s existed little mystery regarding each season’s main villain. Season three is now delving into a slow paced reveal that should be familiar to anyone who’s watched Arrow and The Flash. We know the Legends face an unbelievable threat, Mallus, shrouded in secrecy is the identity of this figure, their intentions, and what they hopes to gain by challenging the time traveling misfits.

Interestingly, there’s no precedent, that we know of, in DC lore to explain who Mallus may be. According to Rip Hunter, Mallus is a threat so formidable that even the Time Masters feared the strange entity, who has supposedly existed throughout time. With followers like Damien Darhk and his daughter, it’s hard to imagine Mallus as anything less than a dark force of magic.

11 RICHARD DRAGON'S ROLE

Kirk Acevedo as Richard Dragon on Arrow

As many may recall, Richard Dragon was initially teased as the big bad of Arrow’s sixth season. However, as the season moves into its back half, it seems that is not the case. Cayden James has taken on the role of main villain, leaving Dragon to appear as merely another minor player in James’ recently unveiled circle of co-conspirators.

Dragon first debuts as a crime lord whose gang breaks into a tech facility to steal hardware. The character’s also later revealed to be the distributor of the narcotic Diggle uses to steady his nerve damaged-arm. With the little known about their connection, Dragon’s overall role seems heavily contingent on whatever Cayden James has in store. But his association with the League of Assassins in the comics may mean his presence on the show runs deeper than we’re currently being led to believe.

10 WHAT "THIS HOUSE IS BITCHIN'" MEANS

The Flash's This House is Bitchin' code

Deciphering Barry’s symbols from the Speed Force is one thing. Making sense of its translation,“This House is Bitchin’,” is another. Cisco deduces the drawings are a code, a mess of unique symbols that in essence are comparable to the structure of the Greek alphabet. Inputting his theory into S.T.A.R. Labs’ computer turns up the puzzling translation. What makes this interesting is the saying’s repeated use.

On multiple occasions, Joe and Cisco utter the line in jest. Therefore, the brain trust behind The Flash, while not allowing the team to linger too long on the symbols, seem intent on ensuring no one forgets these four words. Do they equate to something beyond the strange code? Perhaps it’s another red herring from The Thinker, an effort to keep Team Flash away from the code’s true meaning. Team Flash agrees, it doesn’t sound like something Barry would say.

9 REIGN'S PURPOSE

Odette Annable as Reign on Supergirl

From the outset, Reign is seemingly being positioned as somewhat of a female Doomsday -- a weapon created on Krypton to destroy whatever target it’s programmed to strike. In truth, this bears resemblance to the villain’s comic origins; although, the two differ in how they came to develop following their creation.

Similar to Kara, Supergirl’s version of Reign arrives on Earth as an infant and is raised by humans. Instead of being destined to protect and preserve life on Earth, she’s meant to destroy it as the Worldkiller. As things currently stand, this notion does not yet seem fully realized. For what purpose was she originally created? Are there others like her, akin to the multiple Worldkillers in the comics? And what makes her more powerful than Supergirl? If Reign’s to finally present the Girl of Steel with a truly formidable foe, here’s to hoping character development treats her well.

8 WHY MALLUS SINGLES OUT SARA

Caity Lotz as Sara Lance in Legends of Tomorrow Season 3

In Legends of Tomorrow’s midseason finale, amidst a battle with Vikings and Damien Darhk, Sara is pulled into what appears to be a different dimension. The area surrounding her is dark with a blue hue; at first glance, it seems a desolate place as nothing but sand and a lone tree empty of leaves are visible. During their brief time together, Mallus presents himself as a disembodied voice, speaking of the “unendurable pain” he’ll soon unleash on the world.

There are a slew of questions that need answering, but one in particular is in regards to the villain’s singling out Sara. One fan theory suggests her having died is a possible reason. Considering Mallus has purportedly existed throughout history, a connection to death isn’t unfathomable. Could this mean the Arrowvese is about to dip its toes even further into the occult? It certainly helps explain John Constantine’s much anticipated return.

7 CAYDEN JAMES' TRUE MOTIVES

Michael Emerson as Arrow's Cayden James

At this point in Arrow season six, Cayden James seems intent on getting revenge as he believes Oliver is responsible for the death of his son. How he plans to enact his vengeance remains a mystery, since the hacktivist has continuously harassed Team Arrow with red herrings, one of which may potentially lead to Felicity Smoak taking the fall for whatever his true reign of terror entails.

With an eclectic team of his own, consisting of Black Siren, Richard Dragon, Vigilante and Anatoly Knyazev, James’ endgame is even more difficult to deduce. Why these people specifically and what purpose they will serve a hacker on A.R.G.U.S.' most wanted list are but a couple of questions in desperate need of answering before season six winds to a close.

6 EXPLAINING THE THINKER'S "ENLIGHTENMENT"

Neil Sandilands as The Flash's The Thinker

For all anyone knows, Clifford DeVoe and his wife Marlize have truly good intentions, which could perhaps be a first for any Arrowverse big bad. The Thinker and the Mechanic don’t appear to covet world domination, nor do they seem impassioned to watch Earth-1 devolve into chaos of any kind. So what do the ambiguously villainous power couple aim to achieve? According to The Thinker himself, an “enlightenment” is their ultimate goal.

Frustrated by society’s stunted intellectual growth, The Thinker begins his crusade in an effort to possess all the knowledge one could ever want. The specifics on how he plans to utilize said knowledge is what’s muddled. What constitutes his idea of enlightenment? And how will he and his wife convert this information into supposedly empowering the rest of humanity? These puzzling aspects of their plan aren’t clear, but hopefully this won’t remain the case for long.

5 WHAT IS "THE DARKNESS" IN THE 31ST CENTURY?

Legion Flight Rings on Supergirl

When explaining the Legion to Kara, Alex, J’onn and Winn, during Supergirl’s midseason finale, Mon-El and Imra speak of a “darkness” that’s “spreading” in the 31st Century. What the darkness may be is currently unknown; however, it has the future in perpetual chaos, which Mon-El cites as the inspiration for founding a team of superheroes. The Legion works with the governments of Earth, acting as peacekeepers on the ground and in the stars, meaning that whatever is corrupting the future isn’t exclusively a global issue.

Considering time as a significant factor, it’s possible the 31st Century in which the Legion are residents suffers from the effects of Reign’s potential defeat of Supergirl. Could The Flash levels of course correction with regards to the timeline be seeping its way onto Supergirl? It’s not beyond the realm of possibility.

4 WHY ABERRATIONS ARE FOCUSED ON THE LEGENDS' PAST

The Atom and Young Ray Palmer on Legends of Tomorrow

Thus far, this season, most of the aberrations the Legends have faced are directly connected to some of the team members’ past. The show has debuted young Ray Palmer, brought back the younger Martin Stein, introduced Mick Rory’s father in the Vietnam War, and it seems as though the John Constantine-centric episodes will delve into Sara’s youth.

Legends of Tomorrow’s midseason finale left the team aboard the Waverider pondering the same question. There could be a connection between the aberrations and the villain Mallus, but that the Legends are in the middle of it all is certainly odd to say the least. Each of the aberrations have been somewhat life threatening to their targets, and there’s no doubt the trend will continue since Constantine is now involved. The explanation for why this is happening should be as fascinating as the aberrations themselves.

3 WHY SECONDARY VILLAINS ARE JOINING CAYDEN JAMES

Cayden James and Anatoly on Arrow

In Arrow’s midseason finale, Black Siren, Anatoly Knyazev, Ricardo Diaz/Dragon and Vincent Sobel/Vigilante are all revealed to be working alongside Cayden James. Therefore, as Team Arrow faces division, James’ small group of criminals flourishes. It’s as though he is assembling an Injustice League, a notion that could prove interesting as season six progresses.

Also of potential intrigue is each members’ individual motives. They all appear to have issues of some respect with Green Arrow, but why choose to work with the likes of Cayden James? This is especially curious when considering that at least Black Siren doesn’t know what James has planned, and she’s the only one previously known to be aligned with him. With the development of two teams to service, as well as a slew of other background narratives, it would behoove the show to provide exposition sooner rather than later.

2 WHO WAS THE WOMAN AT THE WEST-ALLEN WEDDING?

Mystery Woman at Barry and Iris' Wedding

The “Crisis on Earth-X” crossover raised a few questions concerning the wider Arrowverse; some, such as why Superman and Reverse-Flash fight in the future, likely won’t receive concrete answers for a while. However, one conundrum begging for an explanation in the immediate future is the identity of the mystery woman who approaches Barry at he and Iris’ wedding.

Their awkward exchange concludes with her reminding him to say “I do,” but there’s also an uncanny familiarity. That awkwardness isn’t foreign… her behavior is reminiscent of Barry’s. And she kind of looks like a West-Allen descendant. Of course, this has left many to speculate she’s Dawn Allen, one half of the Tornado Twins aka the children of Barry and Iris. Another theory posits that she’s Jenni Ognats, or XS, Barry’s granddaughter. For now, all we know is she’ll definitely return, according to actress Jessica Parker Kennedy.

1 UPDATE ON MARS' CIVIL WAR

Supergirl and Martian Resistance Fighters on Mars

One of the more compelling storylines of Supergirl’s third season involves a secondary plot that’s, so far, been minimally explored. During the third episode, Supergirl and J’onn travelled to Mars, offering their help to M’Gann and the Martian resistance fighters. Securing H’ronmeer’s staff to ensure the White Martians can’t so easily eradicate the rebels is but a single hurdle; as M’gann explains to J’onn, there still exists a long and arduous fight ahead.

In past seasons, the happenings on Mars have been largely kept to examining the past through J’onn’s point of view. With an ongoing civil war raging and a beloved character like M’gann taking part in the fight, we can only hope the struggles of Mars won’t be too often relegated to background details. An update on how the resistance is faring would be but one way of keeping viewers in the know.