Hap'he
From Cute and Cuddly. It is bewildering how the most arrogant and stuck up of the Azerothian Archivists can't help but create the most adorable arcane familiars. Perhaps... Magic type. During heavily-restricted PTR testing the only thing affecting the progress was the Weekly.
The 
Hap'he is an arcane familiar pet awarded automatically upon completing the Finally At Rest achievement, which requires turning in The Big Dig: Traitor's Rest Weekly multiple times.
Guide awaiting review
Complete the Weekly Quest
Complete The Big Dig: Traitor's Rest Weekly repeatedly — each turn-in contributes approximately 17% progress toward the Finally At Rest achievement, requiring at least 6 completions in total.
Claim Hap'he from Bags
Once the Finally At Rest achievement is completed, Hap'he will appear directly in your bags automatically — no additional steps are required.
Tips
You can speed up progress by completing The Big Dig: Traitor's Rest Weekly on multiple different characters, as progress is not strictly character-locked, potentially reducing total time to around 6 hours.
