The three-eyed beast attacked the alien and pushed him onto the ground. Though scared, the alien named Xylantro felt that the animal meant him no harm, but was just frightened and its response to a threat is to be aggressive. So he accepted the fake mauling and waited it out until the dog-like creature felt reassured enought to have marked its dominance.
After what seemed like an eternity, but in reality was closer to two minutes, the fight turned into a rough play and eventually faded into a cuddle session.
The bear-sized creature seemed to have taken a liking in belly strokes and by this point it had succumbed to Xylantro's soothing touches. It lay happily on its back and smiled at the alien while greedily accepting the warming touches.

The travel from Xylantro's home planet had taken over 20 plurials, turns around his home star DeXY3220 or approximately 3000 revolutions around the sun )earth-years). Though he had spent most of the time in cryo-sleep, a good chunk of the journey he had to stay awake. For a species as sexually active has his, even half a plurial left him on the edge of bursting nuts, so blue they had gotten.
It was of no surprise then that he saw something else in the smile and submission of the beast...
The stroking got more intensive, built tension and Xylantro noticed that his touch had an effect on the hound, too. He noticed a big bulge appearing from the lower groin of the beast that started to emerge from the fur.
Not much longer until the beast had a full-grown erection, which even though was new to Xylantro, he knew immediatly what it was and what its purpose is.
And so they embraced each-other in a deep hug and slowly, but assuringly, the beast nudged bit by bit of his enormous specimen into the cloaca of the alien. It hurt at first, but Xylantro's species had a unique feature of instant tissue regrowth and shape shifting, so he could accept the welcome intruder in his depths.

Engulfed in their passions, they drove each-other to their respective orgasm. When the beast spew his seeds into his groin, Xylantro was pleasantly surprised.
Though his culture is gendered, all individuals of his species are hermaphrodites and the act of mating is similar to that of slugs, piercing each-other with a sperm-speer.
It was hence positively surprising to Xylantro when he felt the warm, soft and fluid seed exploding in his insides. At first he didn't know what to think, but he sure didn't lack any feelings of lust and pleasure!

After they had come down from their mental bliss, Xylantro thought to himself that he's going to call the dog-like beast, which turned out to be a good companion, "Buster" as it had just bust a huge load into him.
Though he didn't even know of the language spoken by the dominant species on this planet, he had unwillingly chosen the most generic and boring name for a dog the humans had ever come up with.