I mean, in the world of Image Comics, the idea that Science Seance Dog, your favorite childhood comic character, showing up in real life and claiming to be real, in a world with a million and one magic/shapeshifting/superpeople, it makes a lot of sense to think "this is clearly a trick and probably dangerous, given who and what Mark is.

Also, Mark is just… gonna be all over the place in this season and the next. It’s not a ruined character, it’s a kid with anger issues, super powers, and a fuck-load of trauma. He’s gonna do a lot of stupid shit. He’s gonna make a lot of bad calls. And those decisions and mistakes and actions will come back to haunt him. They will change him, he will learn from many. That’s the story. That’s the point of the story.

Mark learns to be Invincible and how to change the world.