Disclaimer: I don't own Hotch or Criminal Minds, though I wish I did (especially Hotch). The name Mercedes came from a book series that I'm currently reading By Patricia Briggs, and Lynn is a shortening of my own middle name Katlyn.

The first thing I can remember clearly is playing baseball with Spencer and a bunch of neighborhood boys. We were on a little league team that our father couched; I was the only girl on the team and the best player. Spencer didn't like playing and wasn't very good at it.

We overheard some of the parents talking nearby. "I've never seen a set of twins so different. They're both extremely smart, but Mercedes is so athletic and Spencer is so clumsy he can barely function." One of the mothers said. Spencer looked down ashamed. I was up to bat, when I got to the plate I gripped the bat hard in anger. I hit the ball directly at the tree next to the woman who put Spencer down, the ball hit the tree hard and the woman screamed. Dad grounded me for two weeks.

*** Criminal Minds***

When the two weeks were up Spencer and I went to the park across the street to play chess. We almost always played with adults, so when a man came up to us and asked if he could play we didn't think anything of it. We played for awhile and the man talked to Spencer, only to Spencer. The man's voice was a color I didn't like. "We need to get home for dinner." I said. I didn't wait for the man's response, I grabbed Spencer's arm and pulled him away. We walked quickly home, I told Mom as soon as we got in the door. "I didn't like him Mom. His voice was a bad color." I said. Mom nodded, she always trusted my bizarre explanations of things.

We moved a week later. Spencer and I were 4.

*** Criminal Minds***

Dad took me to several doctors over the years because he thought something was wrong with me because my senses were extremely strong and I see colors when I hear sounds. The last doctor took a scan of my brain. "The part of her brain that processes senses is very enlarged. That with the symptoms you both described leads me to believe that Mercedes has a condition called Synesthesia. Where her senses are, in a way, crossed." The doctor said.

"How do we fix it?" Dad asked. The doctor made a face.

"There's nothing to fix, Mr. Reid. There's nothing wrong with your daughter, her brain just works differently than ours." He said. I was 8.

*** Criminal Minds***

Spencer and I were standing in the hallway, mom and dad were arguing again. Spencer grabbed my hand and I could tell from the way he was trembling that he was crying. I squeezed his hand and he leaned his curly head on my shoulder. Then I heard the front door open and I let go of Spencer's hand and ran out towards the door. My dad was in the doorway holding a suitcase. "Dad!" I called out. He turned to look at me.

"Mercedes, take care of your brother." He said and then he was gone. Spencer and I were 10 and sophomores in high school.

***Criminal Minds***

We were 12 when we graduated high school. Spencer and I got scholarships to Caltech. Where Spencer got PhDs in Mathematics and Engineering and I got PhDs in Behavioral and Social Neuroscience and Engineering. From there, I go to Harvard and study Psychology. Spencer goes to Yale and studies Psychology, Sociology, and Chemistry.

A/N: This chapter is the back story, the rest will have less time jumps. Also, Synesthesia is a real condition that is a bit different for everyone who has it. Please feel free to Google the specifics like I did.