The Arrowverse is such a sprawling universe with so many characters and storylines constantly in flux and that is why it has gained such a large fanbase.
With such a large world and so many characters, it can be hard to keep characters consistent when they need to serve the larger purpose of the story for each season. This rings especially true to the characters that have been around the longest. Let's take a look at some of the biggest character inconsistencies in the connected DC television universe.
Killer Frost's True Potential
When Killer Frost was first introduced as an antagonist on the show, she could do things that would knock The Flash down fairly easily. This has become something of a glaring inconsistency moving forward, as there does not seem to be any sort of actual gauge on what her powers are in the show now.
Since they introduced her as such a powerful force when she was a villain, she seems very tame now. It may be just because she is not willing to kill people, but with powers like hers, there are many ways to unleash them and not murder people. Viewers cannot fully understand her potential when the writers don't seem to know it.
John Diggle's Moral Compass
A man who, throughout the beginning of Arrow, was very adamant that Oliver stop killing and do this "the right way" without so much bloodshed has changed his mind on these things too many times.
The writers do not seem to care very much about what John's actual moral compass is unless it is to coerce Oliver or another character on the show out of doing something. It is something that people in the fanbase of the show have been vocal about in the past and with good reason.
Kid Flash's Speed
Introduced with the possibility early on that he was progressing faster than Barry had and one day he could be faster, the plotline sort of seemed to fizzle out. But then, in the most recent episode, Wally had skills that Barry has never had, once again bringing into question just how fast Wally is.
The writers are the ones who brought this to the forefront from the get-go and yet they have yet to actually address it. It can be quite frustrating for audiences to have such glaring plotholes in a universe with such rabid fans.
Constantine's Motivations
A later addition to the Arrowverse, by way of cancellation on his original network, John Constantine showed up initially through flashbacks on Arrow. This was a smart choice, as it did not interfere with any lingering storylines from the Constantine show that went open-ended.
But when the character joined Legends Of Tomorrow, they did not address the stories from his show whatsoever. It seemed his motivation had changed completely to a character that fans of his show were unfamiliar with. This was rectified in the most recent season, but is still a big inconsistency for the character, especially considering the canceled show is officially canon.
Damien Darhk, Villain Or Not?
A man that has died and come back many times, this character was complex as an immortal being and grew even more complex, it seems, as one that is not immortal. One of the most recent Legends Of Tomorrow is the perfect allegory for Damien and his inconsistency in the Arrowverse. He starts the episode as a villain who Nora must lie to about her whole life, showing that the changes the writers made to him didn't hold after his death.
He even continues acting like a villain after she marries Ray, pulling him close to say he will kill him if he does not leave the Waverider. This makes the audience question why he would agree to walk Nora down the aisle in the first place. He then tries to shake Sara Lance's hand and apologize for everything that he has done. The writers could not seem to decide themselves how to handle this but wanted Damien to walk Nora down the aisle, turning it into another messy bit of writing concerning Damien Darhk. The most inconsistent villain in the history of the Arrowverse was killed off by the writers and fans don't seem too distraught, as this probably won't be the last time.
Barry Allen's Limits
This seems to fluctuate episode by episode and is honestly one of the most frustrating things in the DC TV universe for most of the fans. One episode Barry can phase through whatever he wants as his powers are depleting and the next he needs to try taking Velocity-9 to save people.
From one day to the next, the writers tailor his limit either to the villain of the week or the big-bad of the season and it has become tired and super inconsistent.
Oliver Queen's Backstory
Oliver Queen's backstory told through flashbacks on Arrow was such a cool narrative device, until it became a burden of constant retconning. At some point, the writers started constantly retconning this fact and that fact and making this a lie and that a lie. Until you finally find out that Oliver isn't a man who kept secrets, he is just a straight-up liar to those close to him.
The same man who acted all surprised when Meta-Humans started popping up has apparently seen magic before and fought superhuman types also.
Reverse-Flash's Appearance
This one can be explained away a million different ways and most fans believe the writers just like Tom Cavanagh better in the role. Reverse-Flash said something along the lines of, "I like to keep the face of the man who you thought you could trust." But this still doesn't explain why every single time (even in the future) where Nora is helping him he looks like Harrison Wells. He is then played again by Matt Letscher in Legends Of Tomorrow and fans are expected to believe that this is a time remnant.
So why wouldn't the remnant look like Harrison? All of the explanations are definitely thin. Now fans understand it is just scheduling conflicts, but they could try harder in the writer's room to make the consistency better.
Supergirl's Limits
Really, what are they? Just like with The Flash, we really don't have a consistent idea of this whatsoever. A constant state of fluctuation on this is not what fans want to have to deal with.
The writers should be writing the villains to attack every strength that Supergirl has, instead of just changing what her weaknesses and strengths and limits are to fit those Big-Bad's.
Cisco Ramon's Motivations
No one wants to be helpful more than Cisco Ramon, a man who could not have been more grateful when he got his powers as Vibe. The sudden turn to not want his powers shocked many fans, but it was understandable to a degree as he wanted to live his life.
The fact is that the writers very quickly gave him his powers back and then ripped them away again and then made him yearn for them. This seems more like inconsistent writing than anything and it is very detrimental to the character of Cisco Ramon.