It was an evening like any other Saturday evening. Cordy and Mira were both tired after a long day. They ate dinner and then got into their usual argument over which movie they’d like to watch that night. Aaron tried to be clever and asked them to each tell him (in secret) which five movies they most wanted to watch, hoping that there would be a couple they’d have in common.

There were none in common, of course. Which led to more arguing. Mira finally sighed that The Lion King (on Cordy’s list) was close enough to The Lion King 1 1/2 (on Mira’s list), and agreed to Cordy’s choice. But she threw in her oft-repeated complaint that it isn’t fair that Cordy won’t compromise, and how she always has to do what Cordy wants to do.

The peak of Mira’s frustration came at bedtime, though. While I was turning on Mira’s bedroom light, I heard them arguing in the bathroom. Mira puts her own toothpaste on her toothbrush, and if Aaron or I aren’t in the bathroom, she does it for Cordy, too. This time, I could hear Mira telling Cordy, “I’m not doing it for you, Cordy. You’re eight and I’m only five. Here, you can put your own toothpaste on.” I knew this could end badly, so I started towards the bathroom.

Cordy immediately went into her unhappy whine and starting shrieking at Mira, demanding that Mira stop being a mean sister and ordering Mira to put the toothpaste on her toothbrush. Mira held firm and yelled back, “No, Cordy! You’re older than me – if I can do it, you can put on your own toothpaste!” She then tried to force Cordy to take the toothpaste container.

Aaron came in at this point, hearing the commotion and already at his wits end with the bickering from the two of them. On first glance, I’m sure it looked like Mira was taunting her sister. He turned to Mira and angrily asked her why she was upsetting Cordy by shoving the toothpaste at her.

I watched as Mira held her ground, equally furious and ready to defend herself. Without hesitation, she looked up to meet Aaron’s gaze with a hard stare of her own, tears forming in her eyes, and exclaimed, “Because she’s eight years old! She’s old enough to do it herself!” I could hear the exasperation in her voice.

I stepped in at that point and tried to calm everyone down, reminding Mira that just because someone is older doesn’t mean they can do everything better than someone who is younger. We all have things we’re good at and things that require help from others. That did little to help soothe her sense of injustice as she cried while brushing her teeth, then continued crying as I gently tucked her into bed and wiped away some of the tears.

I understand her frustration. It has to be terribly confusing at times to be the little sister of someone with autism. Cordy was told about her autism a little over a year ago, when we explained what it meant in regards to how her brain works. Mira was told about it shortly after, and because of her age we’ve kept our descriptions simple for her. Cordy has autism, which means her brain works differently than most people. It means she’s really good at some things, but that she can also have a lot of trouble with things that many people might find easy.

Mira knows that Cordy often has limited patience for playing with others and when she does play it’s often only on her own terms. And while Cordy can teach Mira all about Skylanders and Pokemon, she’s not a typical big sister when it comes to serving as a role model for school, social behaviors and personal care. And she’s brilliant with reading, but refuses to help Mira learn to read.

Mira will likely learn to tie her shoes before Cordy. She can already work a button and zipper on her pants while Cordy remains in elastic waistband pants. Mira learned to buckle her seatbelt first. And while Mira eagerly anticipates each lesson in how to be independent and does her part to help the family with chores, any new task we ask of Cordy involves resistance and the need to do it in baby steps to gradually increase her comfort with this additional task added to her routine.

So in order to make things go smoothly and get more done, we do occasionally ask Mira to go above and beyond in helping out. She’s asked to help with the toothpaste when we’re busy. She opens food containers and packages for Cordy at times. She zips Cordy’s coat.

I know she tries to understand, but it doesn’t always make sense to her. Conventional wisdom says that her older sister should be able to do the same tasks she can do and more. And she feels like Cordy gets special treatment sometimes and is jealous of it. Mira does more chores, and even though she’s rewarded for her extra help, she still knows it’s not equal treatment. (Which I suppose is a good lesson for life, although hard on the spirit at five years old.) Mira doesn’t know it, but she benefits from having Cordy as a big sister – she’s awesome at accepting people no matter how different they seem, always doing her best to befriend anyone.

However, Mira is too young to realize just how important she is to Cordy. Being super-ultra-mega social, Mira provides constant social skills practice for Cordy. Mira doesn’t hesitate to tell Cordy when she’s being rude or make suggestions on how she should respond in a particular situation. (Whether Cordy listens or not is another matter.) She forces Cordy to cope with another kid in her territory all the time, meaning she has to share any decision on our daily activities. Like going out of the house, or sharing the computer, or watching TV, which doesn’t always end in arguments. Mira runs into Cordy’s wall of inflexibility all the time, but that doesn’t keep her from giving up. She continues to throw herself against that wall with the unending determination of a child, hoping that someday she’ll chip away at it and Cordy will do something new for Mira.

I’m an only child, so I’ve never understood the relationship between siblings. I know that siblings often fight, but they just as often share a fierce love and devotion for each other. I have no doubt that these two love each other, even with the fighting. Mira feels like an only child sometimes, Cordy feels like Mira is the stereotypical “bothersome little sister” sometimes, and then at other times the two of them are inseparable.

Proof: they do get along now and then.

For now, I wipe away the tears as I again explain to Mira why Cordy needs her help, and then do what I can to make sure Mira feels important to us as well. Her frustration and feelings of injustice are sure to come back again – repeatedly. I can only hope that as she grows, her understanding of Cordy’s differences, her compassion and her generosity will continue to grow with her.