Cosmonauts of the Future, Vol. 1 by Lewis Trondheim & Manu Larcenet

First of all: I'm surprised to see the "Vol. 1" after reading the book; this walks and talks like a standalone. But I suppose it was successful, because it got two sequels. 

I believe Cosmonauts of the Future, Vol. 1 was the first time Lewis Trondheim (here the writer) collaborated with Manu Larcenet (here the artist) - this was originally published in France by Dargaud way back in 2000. They later (along with Joan Sfar) did a few volumes in the Dungeon series, under the Parade subseries, but I think that's been it - according to Wikipedia, they haven't done a project together in two decades.

I think Cosmonauts was aimed at kids, but I could be wrong: it's fairly sophisticated, and the kids at the center of the story are weird kids. On the other hand, it is French, where the ecosystem for comics of all types is deeper and more complex than in North America.

Martina and Gildas are elementary-schoolers, in some fairly urban place somewhere. This is French, so we could call it Paris and probably be right, or close enough. Gildas is new to the class; we see him join on his first day. Martina is already there, and Gildas is given the seat next to her.

Martina thinks everyone else but her is a robot, designed to pretend they're real and make it seem like she's living on normal Earth. Gildas thinks she's wrong: everyone but him is an alien pretending they're real and making it seem like they're living on normal Earth. Despite their differences of opinion, they become friends, tentatively each accepting that the other is real and not a robot or alien.

They then go about trying to prove their slightly competing theses, as a preparation to exterminating the aliens/robots to save Earth. This is in the humorous mode, so their attempts to confound or cause violent harm to people to reveal their robot or alien nature are played for laughs - mostly.

Martina and Gildas do learn the truth, and this is the kind of book where the truth isn't "they're just very imaginative kids, and will grow out of it." It does all work out amusingly, and the kids get to be the ones driving the plot the whole way. Larcenet's cartoony style makes the occasional violence funny, and works well with Trondheim's script, which has quite a lot of long speeches, since these are the kind of kids who don't shut up about about their crazy theories.

As usual with Trondheim, the humor gets a bit dark and existential, but he keeps the kids central and important: this really is their story, and, in the end, it's about how they were right. As I started off by saying, I'm not quite sure where Trondheim and Larcenet could go from here, so I suppose I need to read the sequels and find out. And any book that leaves the reader with a thought like that is clearly a success.