While the scientists at Horizon were mainly interested in seeing if the uplifted mules were now fertile, there was some interest in their physical capabilities. Horses tended to be very well-built in the muscles department, draft horses even more so. And being half horse didn't make Olly or Nelly any less muscular for it. So as soon as the mule siblings were outfitted with exercise clothes, they hit the gym.
Once they were instructed as to how to lift the various weights, the mules started testing themselves. They started with the lighter end of the super heavy weights before quickly working their way up. Part of the reason they were finding this so easy was because of their sheer size. But while donkeys were usually smaller than horses, they were very strong in proportion to their weight. And being part Mammoth Jack didn't make Olly and Nelly smaller than horses. On the contrary, they were bigger than the average non-draft horse. By the time they had gotten to weights they were struggling with, Olly and Nelly were well-past the midpoint for super heavyweights. They may the potential to lift ultra heavy weights, though probably not anything greater than the lower tier.
"I'm even stronger than I was expecting," said Olly as he put down the barbell, having worked up a good sweat.
"Then how comes I'm still a little behind you?" asked Nelly with annoyance, "We were equally strong when we were only on four legs."
"I'm sure I was a little stronger then," said Olly.
"In your dreams," said Nelly.
"Well, I did end up with more muscle mass than you," said Olly.
"And the only compensation I got was this incredibly sexy body," said Nelly sarcastically as she struck a strong, yet seductive pose.
Olly gave an uncomfortable snort and said, "Could you please not do that?"
"You were posing for those girls," said Nelly.
"I'd rather have their attention than yours," said Olly.
"That I can agree with," said Nelly.
Just then, the pagers they were given started to buzz. It may not be cutting-edge tech, but it was useful for simple cases. Such as informing Animalians that their tests were ready without risking them accidentally breaking phones with their new hands.
"I guess it's time to learn if I'm packing a loaded gun," said Olly.
"Just keep that gun pointed away from me," said Nelly.
==========
Dr. Banjo wondered briefly why he was the one who had to speak with the mules about this. But Dr. Stein and Judy tended to be busy with a lot of things. Well, he didn't have to go into explicit detail about this.
"So, we've done a basic test on Olly's seed," said Dr. Banjo, "And by all indications, he's as healthy and virile as any stallion or jack."
"So, this mean I can mate with horses or donkeys if I want?" asked Olly.
"Perhaps, but your DNA tests indicated you are a separate species," said Dr. Banjo.
"Gee, we're a different species from the regular four-legged mule," said Nelly sarcastically.
"What I mean is the Animalia virus fixed the flaws with your chromosomes, added more than a few human genes to get a balanced count. It would probably be more agreeable to mate with another uplifted mule," said Dr. Banjo.
"I hope you're not implying that should be me," said Nelly.
"Excuse me?" asked Dr. Banjo.
"She's my sister," said Olly, "Maybe being sapient makes know that incest is wrong. But we felt that instinct even before we were uplifted. We just have a better sense of why it's wrong."
"Oh, of course," said Dr. Banjo, "I'm just saying that it would be easier to reproduce with another mule. A converted human would work just as well."
"Great, now we just need to convince some humans to become a species notorious for stubbornness," said Nelly dryly.
"I'm not sure if I'd call you two 'stubborn'," said Dr. Banjo.
"Then what would you call our behavior?" asked Olly.
"Exceedingly sardonic," said Dr. Banjo flatly.
"So what about my tests?" asked Nelly, "Am I just as fertile as my brother?"
"Yours may take a bit more time to process," said Dr. Banjo, "The odds are favoring you, but we can't know for sure until you start menstruating."
"Yeah, that's something to look forward to," said Nelly dryly. Perhaps the mules were not as unbending stubborn as mules were traditionally considered, but the amount of sarcasm they delivered could be enough to drive someone up the wall. Part of it could be explained by the only available mules to mate with were each other, but more mules would be needed to see if they would mellow out with a more viable mate.