So far, there are only a couple of official superhero teams in the film franchise. Every hero has a group of sidekicks or fellow warriors, and some come as a package deal, but the full Avengers Assembly-style movement is rare. With a totally new take on the concept on its way, Marvel has an interesting challenge ahead.

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Thunderbolts is a team of anti-heroes set to join the MCU sometime next year. Reportedly, the roster will be made up of villains from previous MCU films who seek retribution by doing the right thing. The concept of bringing some of the more morally gray antagonists of the franchise back for a new team-up, a Marvel answer to The Suicide Squad, is an excellent pitch. It’s a great way to get beloved characters back into the spotlight and introduce new dynamics between figures who haven’t interacted before. Though no one knows the members of this prospective team, it’s fair to say that many of them weren’t devised with their place on the team in mind. In addition, their less heroic starting points make them radically different from the heroes of the Avengers. With that in mind, fans should hope that the Thunderbolts’ first group outing will be substantially different from Earth’s Mightiest Heroes. Perhaps, however, they could learn from The Defenders.

The Defenders was the eventual peak of the Netflix Marvel universe. Daredevil, Jessica Jones, Luke Cage, and Iron Fist each premiered to differing responses, then came together for the grand finale. This was a fine idea in theory, but countless small problems made it a much less satisfying assembly than that of the Avengers. The Defenders and the four series that introduced its heroes took place almost entirely apart from the mainline MCU, having little to do with its continuity. It’s like a street-level universe that deals with much more personal issues. The modern MCU has folded aspects of that Netflix universe into its unending expanse, though the only aspect anyone seems to care about is Daredevil. Since The Defenders is almost entirely forgotten only five years later, perhaps The Thunderbolts can learn from where it went wrong and where it went right.

The elephant in the room when discussing The Defenders is that one of the four series that made up the team was incredibly poorly-received. Daredevil, Jessica Jones and Luke Cage were excellent intelligent elevations of the superhero format, but Iron Fist was considered substantially weaker than its peers. Iron Fist remains comfortably among the least beloved elements of the MCU as a whole, somewhere below Inhumans but definitely above Hellstrom. Imagine if Thor had been a considerably worse film, then The Avengers just came out with the film’s hero and villain still heavily tied in. The easiest lesson for Thunderbolts to take is to be careful when picking their roster.

This roster issue actually extends beyond the one character no one seemed to like. One of the best things about the Avengers is how different most of the members are in combat. The central members have radically different styles that make them distinct and interesting in group action scenes. Every character has distinct capabilities, weapons, skills, and stylistic visual indicators that make the group fun to watch at once. The problem with The Defenders is that they all boil down to strong hand-to-hand fighters. They’re very distinct characters from a personality perspective, but, when it comes to the action scenes in this action series, they struggle to appear interesting. Aside from Danny’s glowing fist and Matt’s sticks, there’s very little to tell them apart in the heat of battle. When selecting a group of appropriate anti-heroes, they must have different capabilities, or at least different visual signifiers to stand out.

The other significant way that The Defenders lagged was in its villain. Sigourney Weaver’s Alexandra is well-performed and interesting enough as Marvel villains go, but The Hand is an utterly uncompelling mob of henchmen. The Thunderbolts are dealing with a cast of anti-heroes, much like The Defenders’ more morally gray vigilante team, so the antagonist that brings them together should be substantial. Matching the team to an appropriate threat, then making that evil force interesting will be key to creating an excellent team-up vehicle.

There are interesting aspects of The Defenders, but it should stand as a monument to the myriad ways in which this model can go wrong. The Thunderbolts is entering into a very different environment for the MCU and superhero cinema in general, but there’s still plenty that the upcoming work could learn from those who came before.

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