We are living in the age of sequels and reboots, since the industry ran out of ideas and is now simply regurgitating the same franchises. Why risk new stuff when you know the old one will sell by name alone? It’s easy money. With that said, making a sequel is much harder than it seems and is often only managing to damage the image of the original.   

The inherent problem of sequels is forcing a continuation, where the first one ended in a satisfying way. A new conflict must arise, which often renders pointless whatever the characters achieved so far. It feels petty for taking away the happy ending they struggled to achieve. 

It’s extra damaging when the authors have no idea how to continue a story that apparently has nothing left to need another season. They are forced to take away character development, making everyone regressing back to square one with no in-story excuse, and having them repeating the same situations and mistakes as if they never learned from past experiences.

Even when they do not regress developments, the only way for a new conflict to still be threatening, is to be even more severe than the previous one. This is a smart way to make a sequel especially when it feels like the characters are facing threats proportionate to their abilities. Smaller threats are nothing to worry about, bigger ones are beyond their reach and are not affecting or concerning them yet. 

Sadly this is usually not the case, since very few authors can actually make every next conflict to be more elaborate or stressing, often resulting to the issue of power creep. It is constantly the exact same thing with bigger explosions.    

Then there is also the issue of novelty wearing off. If the first one was the introduction to story and cast, anything thereafter does not get a pass because we know the characters and we expect to see something more. This means things must change or the story gets boring for being one of the same without novelty to keep you going. 

The problem with change is that it’s moving away a story from what it felt at first, thus alienating the audience for progressively having less in common with what they liked about it in the beginning. 

A cheap way many are using to avoid this is to constantly introduce more characters and abilities. By doing that, the story is stuck in a perpetually ongoing introduction phase, where the audience keeps seeing new aspects of the setting, without actually changing something in it. Introductions expand it without having to alter it.

Though this too has a problem, since by constantly expanding a roster and the locations of a setting, most lose their importance since there are too many things going on at once and it’s impossible to focus evenly on each and every one of them. Furthermore, newer characters will often be treated as side notes to the older ones, since it takes a lot of time to get used to someone new, as opposed to keep expecting to see more of someone you already invested a lot of time on.      

Which is another issue with sequels. They are slaves to previous installments. They are confined by the restrictions of previous seasons, since they have to follow whatever happened there instead of having the liberty to establish anything they like, however they like it. These limitations include whatever plot holes and inconsistencies the previous arcs established. Although you can retcon excuses later on, you are still forced to keep going with those being canon. 

Down to it, a sequel should feel like a logical continuation from where the previous installment stopped, instead of a shoehorned new conflict that came out of nowhere. But this implies there are plot points than can be expanded from where they were left of, and that they are worth making another season for. Something which is very hard to achieve and is often ending up being just a cashgrab.

https://www.youtube.com/watch?v=HRVU4EStqvg