IxFa notes

Some Amarok notes:
>You worked it up this far for a reason, of course, as you strip yourself down and beckon the wolf to you.
As implies things are happening at the same time, but the working up occurred before the stripping.
>makes it all the more inviting to grab hold
I'm not sure that "inviting" is quite the right word here.
>its thick dark fur
comma after "thick"
>The long flat tongue
I'd recommend going with "its" instead of "the," and there should be a comma after "long."
>The flickering between warmth from the tongue and the cold of the open air
"Flickering" doesn't work here, so I'd recommend "contrast" instead. Also, you should consider going with "the warmth of its tongue."
>the Amarok mounts on top of you
Think you should remove the "on top of."
>does well to improve
Should either be "do much to improve" or "do well in improving."
>that sends an immediate involuntary gasp from you.
"Sends a gasp from you" doesn't work. I'd recommend looking for another verb like "elicits" or "draws."
>The wolf jerks its hips back and in again
I'd recommend adding a "then" after "and.
>pushing another gasp out of you
repetition of "gasp."
>sends all the right signals as it stretches and eases on
Both "sends all the right signals" and "eases on" are a bit awkward. The first because it's usually used to describe indirect communication or inference, but I think the second just doesn't work.
>inner-walls
no hyphen
>and rub vigorously against it in both a sign of affection and a deep involuntary need to distract yourself
I'd recommend "against it both as a sign of affection and from a deep, involuntary…"
>the wolf-cock stays firmly embedded inside with spurt after spurt of canine semen filling your womb.
I'd highly recommend adding a comma after "inside."

I might recommend that you try varying your sentence structure a bit more. Too many "the X does X" sentences in a row can get repetitive.