Roy left Cassau to travel to the capital on his own. He didn't even bring Victoria with her and told her to catch up with Sonia and defeat a lot of monsters. This way, Roy's summoning element will be able to improve at a faster rate. But Victoria need to be able to take full control of the slime before Roy's summoning element could improve.
Victoria fought all the monsters easily, by using her martial arts skill and increasing the weight of her weapons. And whenever she founds an enemy that has a good vision, she would capture them to give to Roy so he can improve his Divine Vision. Most of them are hawk type monster.
She capture them, and put them in a cage that Lina bought. Lina also told Victoria any type of monsters that has good vision. She didn't just look for monsters. She also looked for magic item that will help Roy. She's a very loyal maid.
…although how she became loyal was weird.
Roy just complimented her a few times and she already worshiped him.