Who could be a great antagonist in an 'Alice in Borderland fanfic'?

Another option could be a corrupted version of Asriel. Maybe Alice's arrival somehow stirs up the darker parts of his past and he becomes a force against her, believing she is a threat to the delicate balance in the Underground.

A jealous student could be the main antagonist. This student might have a crush on Alice and see Bella as a threat to their relationship. They could start spreading rumors about Bella, trying to make her look bad in front of Alice and the other students.

The Caterpillar could be the main antagonist. He has always been a bit of an enigma in Wonderland. Maybe as Alice shrinks, he sees her as a threat to his control over the small part of Wonderland he rules and tries to stop her from exploring further.

It could be a new vampire who is jealous of Bella's relationship with the Cullens. This vampire might have some special power that allows them to manipulate memories, like Alice's memories of Bella. They see Bella as a threat to their own plans in the vampire world, so they try to create chaos by making Alice forget about her.

Yes, Alice in Borderland is originally a manga.

I think it's a mystery that's not revealed until later in the manga. You'll have to keep reading to find out!

Voldemort could be the main antagonist. He might see Alice's vampire abilities as a threat and want to use Harry to get to her. He could also be interested in using her powers for his own dark purposes.

Danzo could be a great antagonist. He's always been power - hungry and has a history of using underhanded methods. In a fanfic, he could see the power of the Sharingan warrior as a threat to his plans for Konoha. He might try to either eliminate the warrior or manipulate them for his own gain.

Yeah, it's great! The story is engaging and the art is amazing.

Yes, it is. The story has reached its conclusion in the manga format.