It was a common practice in Berk, the strongest young warrior would claim the weakest as his/her own servant

and husband/wife if desired

(practically a slave), Astrid was the strongest and hiccup was the weakest, it was just fact, and it was just tradition. What wasn’t tradition was the gift of the gods, the divine gift to all residents of berk for uniting the dragons and the people. What this gift actually was, is nothin