Jon Bernthal may get some help from another Marvel hero in The Punisher according to the latest report, but who it will be is unknown. Bernthal made his MCU debut last year as part of Daredevil season 2, which served as a sort of backdoor pilot for the anti-hero. The reception to his casting was great and Bernthal delivered on the hype once he debuted. This resulted in an instant wave of requests for Punisher to get his own series on Netflix, and thankfully Marvel and Netflix felt the same way.
Steve Lightfoot will get to tell Frank Castle's solo adventure, one that will feature him working with Daredevil's Karen Page (Deborah Ann Woll). It was thought that The Punisher would largely stand apart from the rest of Netflix corner of the MCU, but a new rumor states that another Marvel hero could appear as well.
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Not much is known about the story the show will follow - even with a The Punisher teaser trailer now being out - so figuring out what scenarios Castle will come across and which paths he could cross is rather difficult. That said, he has an established relationship with Matt Murdock aka Daredevil (Charlie Cox) already and after saying, "See you around Red," at the end of Daredevil season 2, that may have been foreshadowing for exactly what Cebulski has teased. However, The Defenders left Daredevil in a familiar state for comic readers, and with that set up to be important for Daredevil season 3, having Punisher step on that storyline would be odd.
If it is not going to be Daredevil, it would be very surprising if any of the other Defenders appeared since they do not know Punisher already and are all content with sticking around Hell's Kitchen/Harlem. If known Marvel heroes are off the table, then this tease could be for a surprise introduction of a brand new hero. Could Punisher be where Marvel finally introduces Marc Spector aka Moon Knight? He has a military background just like Frank, so they could conceivably have served together in the past. If an introduction of Moon Knight or a character of similar stature is planned, it would be surprising for that not to leak ahead of time. Marvel has tight security, but this would involve secret casting for a popular character, so maybe now that this rumor is out there, the secret will be uncovered. But for now, we can only speculate as to who could appear if this statement is indeed true.
The Punisher season 1 hits Netflix later this year. Premiere dates for the new seasons of Daredevil, Jessica Jones, Luke Cage, and Iron Fist have yet to be announced.
Source: MCU Exchange