A/N The flashback's set in 1994, the year of my diagnosis. Duck and Michaela present when Erica's revealing why she does things is because they're also something like her. Michaela belongs to FurryFoxFires.

Many years ago, in Erica's home before...

One day, someone came to see Erica, someone new to her. Her railroad's head was there, too.

The stranger explained, "Erica, your railroad's head and your crew called on me because you act different from other engines. You get overwhelmed by noise and are more bothered by smelly stuff than others and sometimes exhibit odd behaviors. I'm an engine psychologist and I'm here to find out why this is so.".

The psychologist observed the blue-ish purple tank engine and told the head of the railroad and her crew Erica had something called Asperger's, a milder form of autism. Erica was told by her engineer* about it one day because she asked why everyone except her oldest brother picked on her.

On Sodor...

Erica had decided it was time to tell her "big brother" why she did some of the things she did.

"Thomas, I, as your "little sister", have decided to tell you and Michaela why I do what I do." There, at the Little Western Junction, Erica told her friends, "I was diagnosed with something called Asperger's many years ago, back at my old home." Erica saw Duck was in earshot, but he was a friend, so it was fine if he knew.

"Me, too," said Duck. "I sensed it on you because I've got some of the issues you've got."

Thomas and Michaela didn't have any problems at all with it, either. Thomas pressed his "little sister's" buffers to let her know and she smiled her cheeky smile just as wide as she could and her dark eyes twinkled, as she engine hugged her "big brother" right back. She gave a happy whistle, full of joy at her friends' acceptance.

Thomas said, "I still think of you as my "little sister", even if you're not typical, I shall still accept you as you are."

Erica, touched deeply by her "brother's" acceptance of her, felt her eyes get wet. She blinked and said, "Driver can you dry my tears?', as one fell down her cheek.

Her driver took a handkerchief out and did as she asked, drying the falling tear and wiping her eyes dry of unshed tears.

She looked at Thomas and said, "Don't worry, "big brother". You genuinely touched my mechanical heart because of how I've been treated. I don't like tears in my eyes because they don't feel good, but I don't like to suppress my feelings. So, I just ask Driver to wipe all those tears away, so I can show my emotion with as little discomfort as possible."

Thomas said, "I know you weren't sad, but I'm happy you thought of me." He flashed that cheeky, sweet smile of his and his black eyes twinkled. I feel so good, he thought, glad his "little sister" was so moved by his words and his engine hug. "I share my emotions with my friends and think it's lovely to get comfort when I'm sad. I like to give it, too because I don't like it when any other engines are sad. You know that because I always do what I can and you know if you're sad I shall always use at least my words to dry your tears**. If I can get to you, then you get my buffers, too, in a hug."***

The three tank engines and one small tender engine got on with their next jobs.

When Erica got back to Knapford, she heard some Troublesome Trucks teasing and giggling. She found out they were teasing her friend Percy about how small he was and he was crying, so she gave him a buffer press. His driver was comforting the little green tank engine as big tears poured from his eyes and wet his face.

"There, there, Percy," his driver said as he gently dried Percy's tears with a cloth. "You might be small, but not too small to be Really Useful."

Percy said with a sniffle as he cried more, "Driver, I hate them talking about my size. I might be a small engine, but I'm hurt by the way those Troublesome Trucks said "We don't want a toy engine pulling us. Especially one who looks like a green caterpillar."

Percy's driver said as he continued to wipe the tears away, "Don't listen to them. Let it go, Percy." He rubbed Percy's cheeks and wiped his eyes.

Slowly, Percy's crying subsided and his driver gently dapped his last tears away. The little green tank engine managed to smile as his driver dried his damp eyes.

"Thank you," said Percy to his driver and his friend. "I feel better." He left the yard with his freight train.

Erica watched her little green friend leave and thought about all the times she ever cried as she went on with shunting. I'm usually a happy little engine, she thought, At least until I get a reason not to be. Like bullies, stress or things that are sensory issues for me. Or someone close to me dying, like my first engineer or driver as they say here I had long enough to bond with, my original fireman and my oldest brother recently. Death, sensory issues and stress can make me wail. I try to keep my tears from anyone but those I trust. However, I can't control my emotions, which means I can't hold the tears back. The best thing about tears is someone wiping my eyes. It relieves the sting of tears and I know it's an act of comfort. Speaking of comfort, I'm so glad Percy got happier. However, those Troublesome Trucks made me steaming mad, picking on my friend and unhappy he was so sad. She finished shunting and was left on a siding while her crew had a break.

Thomas came by after pulling a train, saw his "little sister" on the siding and stopped to talk. He whistled and she responded with her own whistle.

Erica told her "brother", "Asperger's, as my place on the autism spectrum used to be called when I was diagnosed, is why I had echolalia as a baby engine. I repeated questions asked me when I was like a human toddler mentally. Like if someone asked me "What are you doing?", I'd respond by echoing their question. It also makes me sensitive to sensory input, mostly smells and loud noises in my case. I also can't control my emotions, but I don't like the sensation of tears in my eyes. The latter's why I ask "Can you wipe my eyes?" when around any trusted human or shut my eyes and allow an engine friend to comfort me when I'm unhappy. I've wailed over stress and my sensory issues. Here, that would be when I was scared of Diesel 10, you were in a coma, my oldest brother's death or when some really loud noise, like Gordon shouting and whistling or loud noise at the Steamworks. It means I show quirky behaviors, which is why everyone except my oldest brother picked on me in my homeland." Her voice had a sad tone at the end, so her driver, who was just back, patted her comfortingly.

Thomas gave his "sister" a buffer press. "I just like you for who you are, as I showed you earlier when I had you in tears from being so touched. Percy told me how you gave him a buffer press when he was teased by some Troublesome Trucks, the most troublesome of the lot."

They finished talking when Erica had to go back to work and went on with the rest of their day.

A/N *As she's a US tank engine, I used US terminology in this earlier part, as it happened where she was before. **Based on Caitlin and Connor, in a Rosie Angelina fic in which Connor's words dried her tears. ***Refers to buffer pressing being the engine form of a hug. I echoed questions before the age of 4. Erica's meant to be like a child who's mildly autistic because she's based on kid me. Stress and crying meltdowns are reasons a child who's on the spectrum might wail.