Ah, thank you for loving the blog.
One successful way of integrating a non-human into a human society (so that nobody notices they’re not human) is to try a subtle approach when noting their differences.
I’m going to assume you want your readers to know this character is different (even if they don’t know it is an android), so my tip will be geared towards portraying this character in a way that sets them apart from humans, but not enough to betray their true species. For ease, I’m going to call the android a ‘he’ throughout. Please don’t read too much into this; androids, like all characters, can be female, gender fluid or have no gender at all depending on the writer’s intentions for the character.
Every person the world over has their own little routine, and their own habits and preferences. Your android character will be no different, only theirs might consist of things a human routine wouldn’t.
Describe your android’s daily routine. What does he need to do everyday to ensure he’s running correctly? For example, humans need to eat food at regular intervals and our routine reflects this: we have breakfast, lunch and dinner. Therefore, when we see somebody eating out on the street or in a restaurant, we don’t double-take or comment on it. Eating is normal behaviour.
So what is normal behaviour for your android? You need to know what kind of things your human characters might notice him doing, but not be so concerned that they question his species about it. E.g. maybe he’s more active at night than in the day (the only reason most humans aren’t is because it’s ‘sleeping’ time. Androids don’t necessarily need to ‘sleep’).
I’ll put a link to a previous ask I answered about this in the resources bit, but I’m going to add some things that are relevant to your question.
Generally, if someone has a speech impediment or struggles to verbally string a sentence together, most people won’t openly comment on it. They’ll notice it, but they won’t point and shout aloud, ‘SHE’S TALKING FUNNY. SHE MUST BE AN ALIEN!’
Think about your android’s language and the figures of speech he uses, things that might draw a human’s attention (well, for starters, we don’t refer to one another as ‘humans’, but ‘people’). This is a subtle way of allowing the reader to wonder, without necessarily being able to guess the truth.
Also, Androids, like most other robotic beings, lack human emotions. At least at the same intensity as we experience them. Therefore, your android’s language will be different in various situations to what a human being’s would be. So how would your android respond to these kind of questions/statements?:
'We're going to have a baby.'
'Today is my birthday! Are you as excited as I am?'
'There was a guy selling puppies on the corner three days ago and - and - the box is still there, with just one of the puppies left in it, and I -'
'Watch where the fuck you're going, moron!'
'Hey, babe, lookin' for someone to make you feel special tonight?'
'My leg, it's caught. I think it's bleeding. Oh, God. I can't feel it.'
Remember, empathy is the ability to understand and share feelings. People sharp notice when someone responds in a different way to how they would expect, since the majority of us are capable of empathy.
Androids are a good choice when it comes to picking a robot that can blend in with humans because they’re often made to have a human appearance. If there were to be any differences though, what would they be? Think David from the film A.I. When he tries to eat food like the human he’s modelled off, he has a mini melt-down and his face looks unhinged.
For us, sweating through our clothes or having a period in white pants is mortifying. If your android is focused on remaining secret amongst the humans, what kind of normal bodily functions of his own would he make an effort to cover up?
I always liked the idea of being able to hear an android’s internal mechanisms when you stand close to it. Our intestines and stomachs make noises, so what noises would your android make?
What kind of expressions is your android capable of, too? What do people see when he smiles? Laughs? Mourns? Shouts with anger?
How does he stand and sit? What is his posture like? How does it look in his surroundings?
Think about all of the little differences that could easily be explained or ignored by the humans that surround him. If you point them out, your reader will notice, even if the other characters don’t.
This is the best way I can put it: Imagine you’ve landed on a planet which belongs to slug-like aliens that move super, super slow. You’re just new there, so you run around looking for the nearest life form. Because these aliens have never seen anything move at a fast speed, they panic and flail, or stare in awe. Since running is a normal human thing that we do, you wouldn’t know not to do it unless you were aware it wasn’t right for the surroundings.
Does your android have any similar abilities, that are normal to him, but would appear strange to a human?
This can include impressive intellectual skills, such as completing calculations at high-speeds, reciting large quantities of text perfectly, being able to recreate a model or drawing with accuracy and retaining every piece of information he comes across. Most human beings aren’t capable of such feats, so it would draw attention immediately.
That’s just about everything. Your human characters can notice differences between themselves and The Android, but don’t make it too easy for them to see through him. A lot of people make an effort to explain what they see in human terms, because we have no other way of understanding. So when we see someone walking through our estate at midnight on the dot every single night, we don’t think, ‘This is it. It’s the start of an invasion’. We’re more likely to reason, ‘She must work really late…’ or, ‘I wonder if he has some kind of drinking problem to be out at this time every night?’
By all means let your human characters notice, but don’t let them speculate too much until the evidence is hard to ignore.
I hope this is what you were after anyway and that it helps somewhat… Best of luck!