Skoll the spirit beast must be paired with Hati!
Skoll and Hati are brother and sister and if you love Norse mythology its only proper to pair them together as you take down the burning legion!
http://norse-mythology.org/skoll-hati/
I kinda hoped blizz would add a little easter egg if you paired them together but alas nothing but if you into RP and Norse mythos like me its something you must do!