Who's string and zerfre in fairy tail?

Don't you mean Sting and Zeref, or...~?

Zeref is Igneel in human form ..... my guess not a spoiler :D

Zeref is not Igneel in human form. I'm completely sure about that.

Um...No.Do you mean Sting and Zeref?If so,Sting is a member in Sabertooth,a blondie and the White Dragon Skayer allowing him to deal with light.Zeref is the dark mage and like the strongest mage,he's in the S-Class Exams Arc