It can be seen at the beginning of the movie, when Hiccup and Toothless were flying above the clouds. There, a group of Timberjacks could be spotted. They were later made available in Dragons: Rise of Berk, where his name was first revealed.
Soaring Sidekick is pale brown to mid-dark brown in color and has several reddish-brown spots on its wings.
Soaring Sidekick may well be the leader of the Timberjack group seen in How to Train Your Dragon 2, if there even is one, because much more attention was paid to this individual.