Ciela "Spirit of Courage"

About

She first meets Link when he lands on Mercay Island and takes him to her "grandpa", Oshus. Eventually she and Link begin to travel together along with Linebeck, whom she doesn't like much and often fights with.

After beating the Temple of Courage in Molida Island, however, instead of a colorful fairy, another white fairy much like Ciela appears. Link goes to Oshus, who also has traveled to Molida during that time, and uses his staff to fuse the new fairy and Ciela together, revealing that she is in fact the Spirit of Courage, and whose true color turns to be yellow.

Prior to the game's beginning, Ciela had split herself in two to prevent Bellum from sealing her away like he had with the other spirits.

(Source: zeldawiki)