need background ideas 4 omor art ❗❗

hi!!! first blog here lol

sorry for the low quality image but im making a poster of omori/sunny for my little brother and I need help figuring out the background. If you can't tell from the drawing sunny has this thought bubble surrounding him which makes him become omori kinda so its partially sunny and partially omori so most of the background would be from headspace. I was thinking maybe the park, whitespace, or just the sky of the vast forest.

btw im making a poster of mari for me so that we can match (my lil brother is learning violin, i sometimes play little tunes on the piano, sooooooo...)