We have a lot of hopes for this fairy. Here are our four biggest wishes, based on what we know about her character both in the classic tale, and in the show.
1. Keep her morally ambiguous. Once Upon a Time is often at its best when dealing with the morally ambiguous — there's a reason sympathetic villains Regina and Rumple are two of the most popular characters. In the original tale, Tink has quite the mischievous streak, and it sounds like the character in the show is the same. That, combined with the fact that she has a history with Regina, makes us really hope this fairy has a dark streak, even if she's on our heros' side these days.
2. Make her funny! You know what often mixes well with mischievousness? Humor. The Once Upon a Time writers have a knack for writing witty characters and we have a feeling we'll need all the laughs we can get in the dark world of Neverland.
3. Use her to tell us more about fairies. We're still not entirely convinced the Blue Fairy is as pure and good as she claims, and either way we'd love to learn more about fairies, who are clearly very powerful forces in magical worlds, and so far have been underexplored. Bringing on Tink, especially if she's connected to the Blue Fairy, is the perfect opportunity to explore what fairies are in the OUAT world.
4. Drop the costume. Man oh man do we hope the Disney-Tink inspired costume we see here is only for the flashbacks. Based on that photo, that dress did not translate well from cartoon to real life.