>>102389931>so what's the craze behind the axolotl?
No real craze, it's a kind of salamander with some weird properties that looks weird, it's a real animal.
Alex likes axolotls and thinks they look neat, so he decided to make the god being of his GF multiverse an axolotl. The Axolotl is God in the Gravity Falls multiverse. It is the most powerful being that exists in the Gravity Falls universe. Ford meets worshippers and disciples of The Axolotl in his journies across different dimensions in the multiverse. It is either a good being or a neutral being.
Lots of ancillary materials like the Journal they sold and the CYOA book mention The Axolotl, see the page posted in this thread. That TMoGF twitter account even sold some merch of The Axolotl, it made plush Axolotl Gravity Falls toys I think. The Eastern fandom seems to have lagged behind the Western fandom a bit so Japan and Korea really picked up on The Axolotl in their fan art, they made tons of fan art of The Axolotl at one point and its a very popular character for Japanese/Korean fans, probably because it is so "kawaii."
When Bill Cipher dies, he shouts a message backwards calling out to The Axolotl, seemingly asking The Axolotl to resurrect him. The CYOA page makes it sound like Bill could redeem himself, but it's unknown what The Axolotl would require of Bill to resurrect or redeem him.