Here's the corrected version with grammatical errors fixed:
Slyvio stared at the group with a smile on his face. He looked genuinely pleased with his deceit. He laughed some more before he rose to his feet.
However, none of them looked the least taken aback by his words. They had no idea who he was; it was just that they knew this mission would be very eye-opening for them. A unicorn could come in, and they wouldn't move.
The only person that looked the least surprised was Fjall. He stared confusedly at the large figure that stood on his feet.
"Why do you not look surprised to see me?" Slyvio asked, reveling in the glory that existed within him.
"Who are you?" Mordeu asked uninterestedly.
"Slyvio," Alana answered, "he did not lie about that. He is Slyvio, the messenger of The Fates."
"How do you know?" Mordeu asked Alana.
"I lived with The Fates, and I am well acquainted with Slyvio. He is a trickster."