I sometimes see the concept of Danny being the Ghost King or Prince, sharing his ectoplasm with other ghosts so they can become visible or physical. I also occasionally come across prompts or stories where he interacts with ghost blobs—or where he’s mistaken for an ice meta.
So, what if—let’s say—he gets adopted by Bruce, Clark, or even Barry? Maybe this happens after a bad Fenton parent reveal, or the Fenton parents get arrested for child neglect, OSHA violations, or for nearly starting a war with an infinite, unstoppable dimension of death. Danny ends up being taken in by one of the other heroes—whatever the reason may be.
As Ghost King/Prince, Danny gives off a lot of ecto, and let’s just say that in his free time, he’s tamed a few ghost blobs. Since he wants to keep his identity as King/Prince a secret but still wants to interact with the blobs, he pretends that it's just his meta ability.
So to everyone else, it looks like this meta kid has the ability to summon small, slightly radioactive, slightly glowing, adorable blobs as pets—when in reality, they always follow him around. He just occasionally gives them enough ectoplasm to be visible and physical.
And I know—what about Cujo? Well, Cujo could just occasionally show up, and Danny’s excuse could be that it’s one of his blobs that "evolved" into the form of a dog and now has free rein to run around as he pleases. But Danny can still call on him when needed.
(Optional idea): Let’s say, due to the portal being closed—or maybe just as a result of the accident—Danny is partly blind. I imagine that his human form slowly goes blind over time, but it’s subtle enough that no one notices until he’s fully blind. So by the time the Fenton parents are arrested (or whatever the trigger event is), Danny has already lost much of his sight in human form. He uses the blobs to help him with day-to-day tasks, which only adds to the illusion that it’s just a meta ability.
Also, a cute little idea—regardless of who adopts Danny (Bruce, Clark, or Barry)—someone's definitely going to end up naming the blobs and making tiny hats for them. For example, Damian might name them if Danny’s adopted by Bruce, Jon if by Clark, and Bart if by Barry.
(honestly I might just write this but I’m currently too busy studying )