Disclaimer: I don't own Life with Derek nor the song Mockingbird.
Casey McDonald found herself awake around 1:00 one night, and couldn't get back to sleep. The rest of the household was sound asleep. She made her way downstairs to watch some TV, until she felt tired again. There was nothing good on, but she remembered that some old tapes were brought down from the attic so she went looking through a large box filled with tapes.
Most of the tapes were of Derek, Edwin, and Marti when they were younger. One was: Derek's first Christmas, another was Edwin's first walk, and another was Marti's first birthday. Her attention soon gravitated towards one tape that had no label. She looked through the rest of the box and saw that it was the only one without one. Casey's curiosity got the best of her and she stuck the tape into the VCR.
The video started and it showed a boy no older than 11 in one of the bedrooms. Casey immediately recognized it as Marti's room. She could tell by all the cat objects around. The boy was undoubtedly Derek and he was in a chair reading a story next to the bed containing a very young Marti.
After he was finished, he put the book down and started to leave.
"Smerek will you sing a lullaby like mommy used to?" asked Marti.
"Smarti, you know that singing isn't my strong suit", said Derek.
"Please Please Please!" persisted Marti.
"Ok… here goes nothing", he said.
"Now hush little baby, don't you cry
Everything's gonna be alright
Stiffen that upper lip up little lady, I told ya
Smerek's here to hold ya through the night
I know mommy's not here right now and you don't know why
We feel how we feel inside
It may seem a little crazy, pretty baby
But I promise momma's gon' be alright
And if you ask me too
Smerek's gonna buy you a mockingbird
I'm gonna give you the world
I'm gonna buy a diamond ring for you
I'm gonna sing for you
I'll do anything for you to see you smile
And if that mockingbird don't sing and that ring don't shine
I'm gonna break that birdies neck
I'll go back to the jeweler who sold it to ya
And make him eat every carat, don't worry about that"
"Yeah make him eat icky carrots for selling me a bad bird", said Marti.
"Goodnight Smarti", said Derek as he kissed the top of his baby sister's head.
"Goodnight Smerek", said Marti as she slowly drifted off to sleep.
"Hello, who's down there?" asked a half-asleep Derek who was making his way down the stairs.
"Just me", answered Casey.
"Oh, what are you watching? Duck lake again?" asked Derek.
"No and every half-educated person knows its Swan Lake", answered Casey.
"I got the lake part right. So what is it?" asked Derek.
"An old tape of you and Marti. You know back when you were a caring and sensitive person", said Casey.
"Whoa, I have never been sensitive", said Derek defensively.
"The tape says otherwise D", said Casey.
"Hey I was just being a good big brother to Smarti. You know, the divorce was arguably the worst for her because she thought that our mom left because of her. She didn't really understand what was going on. Doesn't mean I'm sensitive", said Derek.
"Whatever you say D", said Casey.
"I'm not. So anyway, what are you going to do with that tape? Make copies and distribute it to the school?" asked Derek.
"No I won't. Why I mock you for being a good brother", said Casey.
"Well if your finished calling me sensitive, I'm going back to bed. All this talk is making me queasy", said Derek.
"Derek, I'm down here because I can't sleep. Will you sing me a song?" asked Casey.
"No", answered Derek. "Only for Marti and I guess Sally even though she did force me. But since she's gone, only Marti".
Derek went back upstairs and into his room.
"Lucky Marti", grunted Casey.
Derek went to his desk and took out a piece of paper with a half-written song on it. The title read: Casey's Song.
"I couldn't let her hear this just yet, it's not ready".
He put it back into his desk in the drawer with the lock. There was no way that he could take a chance with Edwin snooping around all too often. He hoped that the next time he finds Casey up and in need of a song, it'll be ready. Of course, he won't just readily sing it for her; she'll have to request a song and he will fight with her for a little bit. Nothing about their relationship has ever been easy, so why change now. It's part of the fun, the challenge, and he hoped she felt the same way.