(In this AU, Chara actually left the underground, she didn't die there and she promised to help free the monsters once out)

Chara thought she had finally made a friend, she told him that she needed his help freeing some friends

He said okay and she took him there

Ten minutes after Chara fully explained they started fighting...

"You didn't tell me they're from the underground!" The boy said

"What difference does that make?" Chara said glaring at him

"They're dangerous!" The boy replied

Chara's eyes gleamed in the sunlight

"..."

"IM from the underground"

(Should I make this AU a thing?)