This is actually the first longing letter like poem I wrote but it's so late in the chapter count because I decided soon after writing it that I wanted to make several more poems like this one and in chronological order too so it got pushed to this chapter. So yeah, this is a poem from Shiro to Adam after he finds out what happens to him, like season 7 around the time he went to the memorial wall.
Yearning
You wanted me to stay
To spend what time I had left, together
Because with my condition I was to fade away
But I wanted to fly like a feather
Live my dream of going far into space
Exploring the universe
Boy, I had no idea what lay ahead for this face
I still wonder if I got saddled with a curse
Clueless to what was in store
Ending up with a serious dose of trauma
Getting caught up in an intergalactic war
In all this space drama
Even if there was someone new you were pursuing
Even if we didn't reconnect
I wanted to see how you were doing
But I was never able to check
From this life, you were taken
When I found out, it was like I was hit with an arrow
Like a bad dream from which I cannot awaken
And for that, I feel so much sorrow
I will definitely need time to grieve
We didn't always see eye to eye
Even calling it quits before I decided to leave
But I still wish I was able to give a proper goodbye
If you're watching over me from above
I want you to know, from right now, this very start
Even if I'm given a new chance at love
You'll always have a special place in my heart
~Funny thing is I wrote this in November 2018, so a month before the release of the final season, and I now find it amusing that the last stanza has some unintentional foreshadowing, in that Shiro did end up finding new love, when we see that he got married to Curtis. Side note I have no problem with Curtis, I ship Shiro/Adam and Shiro/Curtis.