Heather's brother Dagur shows up out of no where and asks Hiccup for help finding her. He wants to learn to ride dragons. Dagur sees Heather on the edge and goes the extra mile to protect her.
Dagur unexpectedly shows up Looking for Heather. He wants to ride a Dragon to find her and only hiccup knows. He says he will. When the gang finds Dagur but didn't know where Hiccup is they claim he hurt Hiccup. Hiccup is fine and explains everything