User blog comment:FairyRaven/Fairy Tail Chapter 427: Pitched Underground Battle, Review and Commentary/@comment-5872903-20150411232634/@comment-7418318-20150412072655

Since we have no indication who Lucy might fight (IF she's allowed to fight anyone in the first place) I just took a guess.

Briar seems to me like someone who'd critizice Lucy for the way Taurus talked to her or how Loke was such a flirt, which makes me think it's slightly more likely that Briar will be Lucy's potential opponent than any of the others.

When Lucy fights it never is a simple slug-fest after all. With her Mashima usually tries to get at least some comedy into the fights.

I suppose Mary would also be possible for some cuteish interactions with Aries, but I think Briar is more likely.