Just as it felt like all your insides were melting and bubbling inside you, your skin started to thicken and burn as it changed color into a grainy carbon-gray hue. The bones inside you thickened and and lengthened until you were much taller and stronger. You soon had a feeling in your lower body that you had never felt before. It was... it was... the ability to move your legs! Could you...? Yes! You could stand up now! It was a gradual and partial motion, and you quickly sat down again because there was no way you could keep your balance with all the sensations flooding your body and mind.
Fine black hairs sprouted all over your skin and your fingernails reshaped into blunt cream-colored claws at the ends of your digits. Your legs maintained a roughly human shape but were covered in this alien and skin and fur, and your humanoid feet got claws too. Your big toe did shrink to be more similar in size to the rest, which felt kind of odd.
This was getting really weird, and you weren't sure that you should have decided to transform yourself so hastily, but who knows, it might be really awesome. Your facial bones and muscles rearranged until you had a muzzle instead of a regular nose mouth. Oddly, you could smell all kinds of strange residual presences all over the room you were in: distinct scents that were clearly recognizable as belonging to distinct individuals. Unfortunately, you couldn't match the scents with names or faces, since you hadn't really met any of these "people" (aliens) in person yet. The scent of your new alien skin oils was the freshest, since you were the only one actually in the room at the present moment.
Your ears grew up high above your head and began to twist around. You could now hear all sorts of beeping noises that maybe had something to do with the ships functions. Maybe they were some kind of computer output understood by the alien engineers.
Your eyesight changed a little. Most things looked almost the same as before, but you could now see glowing lines and squiggles all over walls. They moved and changed as though they were some kind of computer output. You couldn't really describe them as a screen, just glowing designs emanating from the nickel-colored walls. There were two canine-headed beings displayed there, and one of them was looking at you with awed excitement. Maybe this was the alien who'd been talking to you. The aliens' visual interface must be at a frequency humans can't see, you realized. That's why the room looked so plain before.
Your innards gurgled one more time, and everything seemed to be finished. You noticed that one of the black dog creatures on the wall was moving just like you did... it's your very own image! That part must be like some kind of hi-tech version of a mirror. You tentatively picked yourself up again on your newly working feet and wobbled yourself closer to the "mirror". You pulled back your thin black lips and saw your big sharp teeth. This was so weird.
"Congratulations on your successful change," said the other alien again. This time you could see him talking to you through the smart-wall.
"Thanks," you say, down over your clawed hands again. You look back up to your new friend's projected image. "Hey buddy, what was your name again? I didn't catch it."
He seemed surprised and said, "I am Spokesperson Ngrrrlfangr. The name is that of a supernatural hero in the mythology of our homeworld. It very loosely translates to 'Night clouds after twilight', but the times of day on our planet are not closely analogous to Earth's."
You let out a curious snort through your new muzzle (apparently some of their emotional expressions are different) while rubbing a hand over your new short fur.
"So I'm some kind of weird... hyena monster now?"
It was Ngrrrlfangr's turn to snort. "Hyena? Hyena..." He seemed to be trying to figure out the word. Perhaps it didn't translate very well and he had to look it up. Finally his eyes lit up and he clicked his tongue in recognition.
"Hyena... I see! Non-sapient quadrupeds from the terrestrial order 1559983142, known to your scientists as Hyaenidae. And the answer is no. Your new species is not 'hyena' but 'Jgklfurnackler'."
You don't think you're ever going to be able to pronounce that.
"Although I must admit," he continued cheerfully, "that some members of your species whom we visited centuries ago described us as humans with heads like a similar quadruped from the same continent. Your people seem to call them... 'jackals'." He emitted some raspy, repetitive gasps which you took to be laughter. "It really is a funny anecdote, actually. When a multispecies interstellar research team came down and asked the dominant culture to offer us volunteers for our own early biological experiments on humans, our translator wasn't nearly as good at handling Earth languages as it is now. They thought we were asking them to put dead bodies into giant stone monuments. Their priests painted the diverse likenesses of our research scientists. They even offered sacrifices to a Jgklfurnackler medical expert as their god of death! Needless to say, we don't make such open contact with your civilization anymore most of the time."
Wait, jackal-headed gods? Dead bodies in stone monuments? Cool! He must be talking about the ancient Egyptians. This new alien race you've joined must be thousands upon thousands of years more advanced than humans. This is going to be incredible!