Gaius is the King of Liese Maxia in Tales of Xillia 2 and appointed Rowen as the Prime Minister. He’s trying to resolve diplomatic issues with Elenpios, so to understand the social strata Gaius disguises himself as "Arst" to hide his true identity. Gaius’ special ability is Revenger. Activate this and Gaius will catch an enemy’s attack, do a front step, and strike back with a powerful blow.
Musee, Milla Maxwell’s older sister is also in Tales of Xillia 2 as a playable character. Her special ability Rev-attack lets her do a front step or back step when she gets knocked back.
Namco Bandai changed the orb system for Tales of Xillia 2. A new orb absorbs specific elements like earth, water, fire, wind, light, and darkness during battle. There is a different ring for each element and you can use points (lighting for the lightning ring, for example) to acquire new abilities. You’ll need to work on all of the rings because some skills require say fire and wind to get one skill.
Tales of Xillia 2 also has a cat sidequest. A woman who lives in the same complex as Ludger will ask you to look for her cat. After you find it you can send the cat on quests to fetch items. After some time passes the cat will return with materials, weapons, and/or attachments. Namco Bandai also confirmed attachments (items you use to decorate characters) from the first game will be in Tales of Xillia 2.