Board Thread:False Info and Speculative Discussion/@comment-26781694-20160309171151/@comment-4091815-20160519175929

In teen wolf, as Jeff says constantly, pack = group of friends. It's part of the "choose your own family" thing that is most common among youth culture in urban areas. These chosen families often have bonds much stronger than biological analogues.

That's the metaphor the writers are working with, as I understand it, when they put together Scott's pack.

To return to the discussion at hand, Mason and Liam were already pack prior to the bite. Liam didn't leave his pack to join Scott's. Like many friend groups, they merged and all became family. He solidified his place in the group with his assistance on the Escape from Eichen and they fought to save him, as a pack would, when he was taken over by the beast. He's totally pack/fam.