SPOILER ALERT: This story discusses major plot developments, including the ending and post-credits scenes, in “The Fantastic Four: First Steps,” currently playing in theaters.

From the very first scene, the question of what will become of the child of Reed Richards (Pedro Pascal) and Sue Storm (Vanessa Kirby) looms over “The Fantastic Four: First Steps.” When Sue tells Reed she’s pregnant, his thoughts immediately turn to what it means for two people with superhuman DNA to procreate. Reed puts the fetus through every possible test he can, and nothing indicates anything is abnormal, so it comes as a shock when the massive, primordial, world-eating Galactus (Ralph Ineson) announces that Reed and Sue’s child does, in fact, possess “the power cosmic.”

Reed, Sue, Johnny Storm (Joseph Quinn) and Ben Grimm (Ebon Moss-Bachrach) are too busy keeping Galactus from taking Reed and Sue’s child once he’s born — oh, and also consuming the entire planet Earth — to find out what it means for wee Franklin Richards to have the power cosmic. But they get a pretty strong idea after Sue dies using all of her power to push Galactus into a giant teleportation portal. As Reed, Johnny and Ben weep over Sue’s body, baby Franklin reaches out to her, places his hands on her shoulders, and, after a few moments, Sue’s eyes become filled with stars as she gasps back to life.

Comic books being comic books, the boundaries of the power cosmic haven’t been rigidly defined, but it is essentially the power of a god, with the ability to manipulate just about anything at will — including time itself. As a storytelling device, this level of almighty omnipotence can be dangerous: How can anything matter if your character can fix it all in a blink of an eye? To repeat: In “The Fantastic Four,” Franklin saves his mother from death as an infant. Imagine what he’d be able to do as a toddler, or a teenager.

Marvel comics have dealt with this problem by taking Franklin’s powers away from him — sometimes he does it voluntarily, sometimes it happens with external restraints (often placed by Reed). But while the power cosmic itself can be deadly for drama, the fact that a child possesses this power has also proved to be a fertile creative engine in Marvel comics, attracting all manner of villains bent on manipulating Franklin into their own nefarious machinations.

Which brings us to the mid-credits scene of “The Fantastic Four.” Four years after the events of the film, Sue and Franklin finish reading the classic children’s book “The Very Hungry Caterpillar” (which was first published in our reality in 1969). She gets up to find another book — H.E.R.B.I.E. the robot suggests Franklin’s favorite, Charles Darwin’s “The Origin of the Species,” but Sue wants “to go for something a little bit more fun today” — and as she walks back from the kitchen, she hears something…off. She walks slowly into the living room, activating her forcefield powers, and sees a man in a green, hooded cloak, kneeling in front of Franklin, as he brandishes a silver mask.

Although we don’t see the figure’s face or hear him speak, this is obviously Doctor Doom, who will be played by Robert Downey Jr. in 2026’s “Avengers: Doomsday.” In the comics, Doom is an integral figure in the lives of both Franklin and his younger sister Valeria, as kids and adults — occasionally at the same time, through the magic of time travel and the multiverse. Given that “The Fantastic Four” takes place on Earth-828, and we see their ship appear on Earth-616 in the post-credits scene in “Thunderbolts*,” it’s clear that “Doomsday” will freely traipse the lines between time and space within the MCU. And now it appears that Franklin will play a critical role how that all comes to pass.

On the one hand, this is a terrific way to bring the Fantastic Four into the larger MCU: It isn’t about some abstract metaphysical danger, it’s about their son, creating an emotional hook into a story that — with at least 27 major speaking roles — could otherwise become unwieldy. And unlike 2018’s “Avengers: Infinity War,” “Doomsday” isn’t benefitting from years of earlier blockbuster movies establishing the central villain and defining what’s at stake for the characters. Audiences just aren’t as invested in the Multiverse Saga as they were in the Infinity Saga, but a family desperate to save their child is an easy story to connect to.

On the other hand, while Franklin’s abilities seemingly outstrip everyone else in the MCU, he hasn’t been established yet as an actual character beyond being a cute, towheaded preschooler. Hinging “Doomsday” on our investment in an all-powerful cypher is doubly dangerous for a blockbuster movie — which is another reason to wonder whether an older version of Franklin from the future may show up in “Doomsday,” as he does in the comics. (It is…curious…that Sue is reading a Franklin story about metamorphosis into a butterfly, followed by a reference to the man to discovered the theory of evolution. Most curious, indeed.)

If the first post-credits scene in “The Fantastic Four” is a portent for Marvel’s future, the second was an homage to its past. After the final credits roll, a quote from “Fantastic Four” co-creator Jack Kirby (no relation to Vanessa) appears on the screen: “If you look at my characters, you will find me. No matter what kind of character you create or assume, a little of yourself must remain there.” Kirby’s birthdate of August 28, 1917 appears next to his name, revealing that it corresponds to the Fantastic Four universe of Earth-828 (i.e. 8/28/1917). Then the opening credits of the in-universe Fantastic Four animated series plays, with a peppy theme song that evokes the Saturday morning cartoons of Marvel characters from the 1970s that inspired “The Fantastic Four” director Matt Shakman as a kid. It’s such a blast of nostalgic fun, perhaps Marvel should consider making that show for real.