Or, Aslan or Vargr might have keen senses of smell. Again, it could make a big difference in terms of how they act and react.
T5 has the Senses section (T5.10 Book 1, p.186-199), which details how the senses respond
per species, as well as two additional standard senses that humans do not possess. Each species has a sense constant that determines how sensitive that particular sense is for the species as a whole, as well as its operational range, so that when using it to detect/notice something, those with a higher species-constant will be more likely to notice. Hearing range is species specific, and sight-range is relative to the light peak-frequency of the home-star of the species origin world.
Maybe they can only see certain colors and are color blind to others?
The T5 version has a lot to say about this in terms of what they can sense. Sadly it did not make a lot of sense to me but I only read over it in review mode. The common trope of Vargr being colorblind and wearing a cacophony of colorful clothing comes to mind.
In T5 the Droyne sight range is shifted to the
Near-Ultra-Violet ("
Sparkle") to
Orange-Red range (peak at
Blue) and cannot see certain dark-reds (
Cerise) due to their likely F-Type original home star as compared to humans whose sight peaks at
Green peak frequencies (G2 V star).
Vargr sight range and peak are the same as human, but like the canids from which they derive, their vision is dichromatic, seeing violets, blues, and yellows well, but having trouble with reds and greens (a good analogy for Vargr is that they are like humans with Red-Green colorblindness).
I like to think it would be fun if I were creating a Vargr character to come up with a cool "outfit" for him using one of those web-applications that simulates Red-Green colorblindness while I am choosing the coloration of a set of clothes from a palette, get it just the way I like it (and save it), and then turn off the colorblindness filter and see what I came up with, and then save that too. Then I have a version that I record for myself and show to other Vargr PCs, and another version that I show to everyone else's PCs.
And somewhere in the forums there was some discussion on even control colors: humans red = bad, but it may be an entirely different color for other species.
During WWII, the Germans used "Red"-light for trouble, and "White" for normal (as opposed to Green) in their U-Boats. Other cultures may use something entirely different. Or even worse, what if the "trouble" alarm for a species that uses visual cues for controls is in
infra-red or
ultra-violet? Better hope you have those goggles or that Vacc-suit helmet on with the PRIS option.