- "The Great Fairy Cotera... Only a few remain who know this, but this village was built under her watchful eye. The mysterious power of Cotera is that of sacred protection... I suggest you seek her out."
- — Impa
According to Impa, few people nowadays know that Kakariko Village was built under her watchful eye. This implies that she protects it with her mysterious sacred power, thus explains how Kakariko Village and the Sheikah inhabitants survived the Great Calamity then faced the threats of surrounding monsters and the rival Yiga Clan during the Age of Burning Fields.
Since the Great Calamity, few people visited Cotera's flower fountain and she was starting to waste away by the time Link first meets her. Cotera requests an offering of 100 Rupees from Link, or more if she is not the first great fairy encountered, to restore herself to her former glory. Upon being rejuvenated from acquiring the Rupees, Cotera will offer to upgrade Link's armor if Link is able to provide her with the necessary crafting materials. She will propose better armor upgrades once Link rejuvenates her sisters Kaysa, Mija and Tera.
Like her sisters, she shows affection to Link when she upgrades his Armor. For Level 1 upgrades she blows a kiss, for Level 2 she kisses her finger and touches Link's forehead, for Level 3 she kisses Link as he bashfully cowers from her advances, and for Level 4 she suddenly grabs him and affectionately holds him, before pulling him into her fountain, and the screen momentarily fades to black before returning back to the spring where Link is lying on the ground gets up finding his selected armor has been upgraded completely.
Impa's bodyguard Dorian is aware of her existence though is too intimidated to go see fo himself. He is protective of the location of Cotera's fountain keeping that information from outsiders such as the traveling Sheikah painter Pikango whom Dorian is unfamiliar with and suspects may be a Yiga Clansman. However he trusts Link due to his heroic status and being an ally of the Sheikah as well as Princess Zelda's personal knight. Dorian also tells his daughters a scary story to keep them away from the fountain as the area had become dangerous due to Cotera's waning power though his ghost story only works on Koko while Cottla is intrigued by the story.
Related Side Quest
Due to Dorian ensuring Pikango doesn't learn its location, Pikango requires Link to "Find the Fairy Fountain" near Kakariko Village for him and take its picture with the Camera Rune. Link must revive Cotera's fountain to take its picture. After bringing him the picture he will help Link by giving him hints for finding locations for recalling Recovered Memories during "Captured Memories". Dorian's fears about Pikango are unfounded as he was apparently born in Kakariko Village though left it sometime ago to see the world as a traveling painter. Apparently he'd been gone away for so long that none of the villagers recognized him as Dorian noted none of his fellow Sheikah recognized Pikango in his Journal of Various Worries entry which caused him to view Pikango as an outsider and suspect him to be a Yiga Clansman. Pikango himself notes it had been a long time since he'd been to the village which had apparently changed over the years and due to everyone wearing the same clothing he ended up making the mistake of asking the same person the same thing multiple times while trying to dig up information on Cotera's fountain causing him to go from being seen as a stranger to a suspicious roamer to them.