Where is the “middle generation “??

[The Cool Thatguy]

It's mostly to do with him being from Isaiah Bradley's lineage, Isaiah being the original African-American Captain America from Truth: Red, White, and Black, a miniseries explaining that the Super-Soldier Serum used on Steve Rogers was initially tested on African-American men in an allegory for the Tuskegee syphilis experiments run on African-American men in real life around the same era. Somehow, there's some kind of legal issue with that entire family tree, which is also why Josiah X from The Crew (Isaiah's genetically engineered son) and Isaiah himself have not appeared in Marvel's comics for at least a decade now.

I don't think Josiah X appeared outside of The Crew, anyways.

I'm still so utterly baffled as to how there could possibly be any legal issues with a mini based entirely on the history and career of a character Marvel has owned for over 4 decades. There's no 'The Truth' without Captain America

[CrimsonEchidna]

As far as which characters catch on and which don't is kind of relative. Like for this most recent "influx" of new teen heroes, you can make a legitimate argument that the only ones that have kind of caught on pop culture wise are Kamala, Miles, and Spider-Gwen.

It all kind of comes down to writers interest in the character. Robbie Reyes for example kind of went into limbo after his original run got cancelled, but reemerged again because Jason Aaron, who effectively got the keys to the kingdom at the moment, has interest in him.

[Digifiend]

Happens with every generation, I suppose, at both Marvel and DC.

New Warriors: Nova was the biggest success. He came back after a decade hiatus when the team launched, and ended up leaving the team in 2006 just before Civil War - thus escaping getting killed off - and became one of the flagship cosmic heroes. Justice and Firestar both joined the Avengers, but neither have seen much use recently. Justice has been completely gone since the last NW book and Firestar is a background character at best in the X books. Whereas Nova can currently be seen in Guardians of the Galaxy.

Young Avengers: Most successful is definitely Kate Bishop, who's had her own book.

Teen Titans: Obviously Robin is the best known, but that's not due to the team. The breakouts are probably Wonder Girl from the first lineup, and Cyborg from the second.

Young Justice: Breakouts here are definitely Impulse and Superboy, who each had his own book.

Avengers Initiative/Academy: This generation flopped completely. They were all in limbo for some time until Hazmat and Finesse were used in Captain Marvel and Unstoppable Wasp recently.

[Huntsman Spider]

I don't think Josiah X appeared outside of The Crew, anyways.

I'm still so utterly baffled as to how there could possibly be any legal issues with a mini based entirely on the history and career of a character Marvel has owned for over 4 decades. There's no 'The Truth' without Captain America

Same here, but I am sadly not versed in whatever dispute is keeping the Bradley family --- Isaiah, Josiah, and/or Eli --- from appearing in comics, especially given what's happened recently. You'd think they'd have an opinion or be doing something vis-à-vis Secret Empire, let alone the current Captain America run actually addressing the aftermath of that.