This is Judith from Tales of Vesperia. The best way to describe her personality is that she is a big tease. She knows she is attractive and does pretty much everything to tease males and Estelle. She enjoys teasing and is a part of her personality. It doesn't mean she holds any feelings for the guys she likes to tease to.
Having said that, she goes well with Yuri simply because Yuri, too, is somewhat of a tease and their personalities match. I doubt they'd make a good couple though. She is completely neutral to everyone, even including Yuri.
Estelle is sometimes seen being jealous of Judith's boob size. In one of battle-end conversations, Estelle is seen mumbling wishing she had the size of Judith's "bouncing" boobs.
If you are wondering what she is wearing underneath, it's simple panties that are the same color as her hair.