It's happened before. A lot of the allies in ww2 were nazi-curious before their country was invaded. They were getting fairly popular in the US especially, holding large rallies and captivating the hearts of several of our captains of industry. I won't go into the details.

Some states will go down the path of fascism until they pass the point of no return, and the state that existed before is well and truly dead. When they're done warring against their own minorities they'll attempt to expand to neighboring states because they need to justify their own existence.

Some states will follow the path of fascism until they see their peers further down the path either trapped in the turmoils of war and genocide, or threatening war and genocide on themselves or their close allies, then they turn around out of fear of the new common enemy. Like a sailor trapped by a sirens call only snapping out of it when the sailor in front of them gets devoured.