This character story becomes available in Chapter 7, Episode 1.
[-] Find a town specialty that’s white.
Head to the marked location and talk to the NPC to receive a magnolia flower. Simply deliver it to Sting to complete the request.
This character story becomes available in Chapter 7, Episode 1, after finishing the preceding character story.
[-] Get Yukino’s keys back from the monster!
Travel to Tenrou Island and head to the marked location to trigger another cutscene. Defeat the golems and after more cutscenes, the request will be complete.
This character story becomes available in Chapter 7, Episode 1, after finishing the preceding character story. For the last character story, you’ll be controlling Natsu and have to defeat Sting in a 1v1 duel. Sting is just LV35 so if you’re over 40 at this point, you should have a comfortable advantage against him. Before starting the battle, make sure that you have the proper lacrima equipped. During the battle, spam Crimson Lotus: Fire Dragon Fist to keep the countering Sting’s attacks and build up your fairy gauge. Once full, trigger a magic chain to finish him off to complete the request. After completing this request, Sting will finally join your party.
We have questions and answers related to this topic which may also help you: