Anyone in charge of the Spider-Man books is going to need a plan for the supporting cast. This is one category which has often been handled poorly.
There have been some suggestions that the book should focus entirely on the supporting cast. I discussed the problems with that approach in an earlier piece. In a CBR poll, an overwhelming majority preferred a title with Peter Parker and none of the supporting cast to an ensemble title with everyone else, but not Peter Parker. So it's important to keep things in perspective. The rest of the cast is important, but not essential.
The ideal is probably the Stan Lee/ John Romita Sr era, with the Mary Jane/ Gwen Stacy romantic triangle, Harry Osborn (son of occasional supervillain Norman Osborn) as Peter's roommate and Robbie Robertson battling J. Jonah Jameson for the soul of the Daily Bugle. The cast could be split into several categories, and there were interesting dynamics to everyone involved.
One of Peter's social circles was the staff of the Daily Bugle. Then he had Aunt May and her friends. And then there were his classmates at ESU. There were also links between some of the groups. Peter's girlfriend's father was a friend of Robbie Robertson. Mary Jane was the niece of Aunt May's friend, and she started dating Harry Osborn.
The supporting cast would sometimes interact with Spider-Man, and they had different opinions of him. Although it's worth noting that it was still Peter Parker's supporting cast, rather than Spider-Man's. The only people who Spider-Man interacted with exclusively were fellow superheroes, or former supervillains like Curt Conners and Hobey Brown. And those guys weren't members of the regular ensemble.
There were interesting things about all the cast members. Norman Osborn was a ticking time bomb, as a man who had forgotten that he was a supervillain. There were times he was targeted by a villain who wanted money owed by the Green Goblin. Flash Thompson didn't care for Peter Parker, but he was good friends with Harry Osborn, and he adored Spider-Man. Frederick Foswell was a former supervillain trying to restore his reputation as a reporter.
One problem with the supporting cast was that it just got too unwieldy. During the Brand New Day era, it included Aunt May, J Jonah Jameson Sr, J Jonah Jameson Jr, Felicia Hardy, Flash Thompson, Betty Brant, Glory Grant, Randy Robertson, Norah Winters, Ben Urich, "Robbie" Robertson, Carlie Cooper, Martin Li, Michelle Gonzalez, Harry Osborn, Mary Jane Watson, Marla Madison, Vin Gonzalez, Sha Shan, Anna Watson, Bill Hollister and Lily Hollister.
A core supporting cast is crucial, providing touchstones and a sense of consistency, but the Brand New Day era cast was so sprawling that this wasn't provided. All sorts of storylines were dropped or ignored for months, such as Harry's romance with Peter's cousin, MJ's reaction to Peter kissing Felicia (which was on the cover of Amazing Spider-Man #606), Felicia's job with Jonah, and the aftermath of Chameleon insulting Flash while disguised as Peter. It's easy to get lost in the shuffle, so nothing comes out of a story that someone teases, even if it's promising. I wanted to see the stories that resulted from Flash Thompson working with Peter at Mayor Jameson's office.
The supporting cast was stretched thin as it was spread across several social circles: Peter's family, his coworkers at Frontline, his coworkers at Mayor Jameson's office, his roommate, people he knew from college, etc. Hell, there were some he met with exclusively as Spider-Man. So there isn't much interaction between many members of the ensemble, and Peter can go along time without seeing the people he's supposed to interact with regularly.
Some of the characters from the Brand New Day era have stuck around. J Jonah Jameson Sr essentially became Peter's stepfather. Norah Winters stuck around because of her personality, and is now in a relationship with a supervillain.
Carlie Cooper was a controversial addition, considering all the complaints when she was either Peter's girlfriend or a potential romantic interest. Now that they've broken up, she's become a different type of ex-girlfriend. She's an interesting addition to the ensemble, a contact on the police force he used to date. The job often puts her into Spider-Man's world. And there's a new dynamic, considering the unique professional risks, potential for philosophical differences between a cop and a vigilante and the difficulty in bullshitting someone whose job it is to be familiar with murders. She's also become a friend of MJ's, due to the things they share in common as ex-girlfriends of a superhero.
The reverse of the Brand New Day problem occurred during the marriage when the supporting cast was often forgotten. One reason was that Mary Jane filled so many roles, as Peter Parker's lover, confidante, best friend and dependent, that there just wasn't room for anyone else to be consequential. The characters who mattered were people Peter had known for a long time (Flash Thompson, Aunt May, Liz Allen, Harry Osborn, etc.) or newcomers who had ties to events in Spider-Man's history, such as Jill and Arthur Stacy, or even Ben Reilly.
Supporting characters are pretty useful in serials. It helps to have a handful of characters as Peter's primary supporting cast, for him to interact with in most stories. This provides touchstones, along with a sense of consistency and consequence, as these people would be aware of prior developments.
Should Marvel decide to go back to the three monthlies approach, I think there's a lot of potential in a Web of Spider-Man focusing largely on one supporting character. Mary Jane Watson could fit the bill here. That type of approach also makes it easier to parallel events in Amazing Spider-Man (and vice-versa) and gives the satellite book a structure/ separate identity. It's something to consider, although the main focus should remain on the flagship title.
In most cases, it seems to me that the title needs a smaller core cast, people for Peter Parker to consistently interact with. It would help to have characters who serve at least two purposes (ie- roommate and coworker.) There can be more ancillary characters, or characters who pop in and out for short stretches, but a clear top-tier core has tremendous benefits.
This seems to be what we're getting with The Big Time. In Horizon Labs, it seems the most significant coworkers are Max Modell (the boss), Uatu and Grady. Because of Horizon Labs's stature, they're often called in by J Jonah Jameson Sr. It's not perfect. The staff of the Daily Bugle hasn't been seen in some time. The only friend Peter seems to hang out with is Mary Jane, although it's worth noting that he's pulling double-duty as a member of the Future Foundation and the Avengers.
If I was writing the book, one possible supporting cast would consist of Aunt May, J Jonah Jameson Sr, J Jonah Jameson Jr, Mary Jane, Harry Osborn, Norah Winters, Betty Brant and a few new characters. The basic set-up would be a media venture by Harry Osborn and Betty Brant.
May Parker could just be the most essential member, as one of the few links to the boy he was before the spider-bite. Jonah Sr's come closer than anyone else to essentially replacing Uncle Ben. Plus he provides a link between the two best characters in the Spider-Man franchise. Mayor J Jonah Jameson continues to be Spider-Man's nemesis, as well as a constant subject of journalistic investigation. Mary Jane Watson can stay, as she's the other most recognizable supporting character. Just to complicate Peter's life even more, she should be dating someone in his social circle, and involved in a project that deserved media attention.
Betty Brant's new media venture would be Peter's job. Harry Osborn could be the financial backer of the projects a new venture, which calls for Peter's services. So, there's that whole dynamic as their friendships are tested by the new business partnership. There are several possibilities here. Peter could be in a subservient position to two of his friends. Or he could have more responsibility in a leadership position, investing some of the money from Horizon Labs.
Norah Winters is a terrific personality, so it would be fun to add her to a series. She's savvy enough to be a significant contribution to a 21st Century media project. A new character could be an accomplished reporter, perhaps a Journalism school classmate of Ned Leeds. This guy could complicate Peter's personal life, and make an excellent first impression on Mary Jane Watson.
Obviously, there are many approaches one can take. A mistake writers sometimes make is an unwillingness to ignore certain characters. Some have complained about Harry Osborn's departure post-Brand New Day, but there wasn't a particular role for him in the Big Time era. I have no objections to bringing him back to the book if he fits well with the rest of the cast. But there's no obligation to have these characters around all the time, if they don't bring anything to the current stories.
Stan Lee and Steve Ditko were right to send Liz Allen packing when Peter Parker went from High School to College. Gerry Conway was right to bring her back when he had a new hook for the character, revealing a connection between her and a minor Spider-Man villain.
The main way to get rid of unpopular supporting cast members was to kill them off, but that's often a bad idea. There are things that some characters bring to a series that no one else can, so it's important to consider the disadvantages of getting rid of someone permanently. No one's been able to replace poor Lance Bannon.