Guila starts off as a sadistic Holy Knight, very determined to stop Meliodas and the Seven Deadly Sins. I never really liked her.
She even half kills herself to fight them in a land that bridges the alive and dead. She’s downright insane.
At a time, her impressive sword magic made even Diane and Meliodas have to seriously defend themselves against it.
After Hendrickson is defeated, we learn she wasn’t all that bad. She was a good sister to her little brother.
When she dated Gowther was pretty weird. She dumps him after he manipulated her memories for fun. Good for her.
She doesn’t do much for the rest of the series except interact with Jericho.