One of the hardest things to do when telling a story, be it at the table or in some other medium, is to convey how strange a species is. One of the next hardest things is to also make those characters relatable still. Today I want to talk about that.
Little Things Mean More
When pointing out how strange and different a species may be from humans, a lot of people go right for the big things. I have nothing against this. The big things can be important. It's good to know a race of clones all look identical, or if they communicate telepathically. Those are all great. However, if you really want to convey a sense of other and strange, you want to hit the little things.
Consider, every human house around the world what things would you expect to find? A table to eat at, a bed to sleep on - or a place where people sleep if bed isn't what they use there, and generally a place to go bathroom. You can say a lot by moving these things around - for example, if someone lives in an apartment with communal bathrooms you immediately get a different sense than one with a bathroom in every bedroom, right?
So what sense do people get when they go into a home and there is no bedroom, but everyone has a personal workspace. A place where there is no kitchen, no table, or anything for eating at home? No bathrooms?
These are common things that people just take for granted. Everything sleeps. Everything eats. Everything poops. Heck, eating and pooping are - by more technical definitions - two of the scientific requirements to be considered a live. So what happens if they're gone?
Making these changes then brings other things to mind to. If the species doesn't sleep, what do they do? How do they 'recharge'? What do they think of species that do have to sleep?
Stacking Up Similarities
At the same time, making something reltable is the opposite. You want something to feel different, you emphasize the differences. You want something to be more relatable you need to play up the 'human' aspects of things. This means establishing some common ground with the players, if not the characters. It means showing places where the creatures are the same. Perhaps they care for their children, or they have similar emotional responses to similar stimuli.
Playing these up with erase some of that feeling of alien, and with that feeling gone you'll have a place for the PCs to relate to this species. Keep in mind though, the more you make a member of the race relatable, the less strange and alien the rest of the race will seem.