I promise I will get the wallpaper uploaded soon. For now, I upload "the making of".
I was inspired by RK-style art, by those 2 manga pages you see there. Then, after letting the idea vegetate for a long, long, long, long time, I got this crazy KH idea (I have no idea where it came from) to put Terra in that same setting.
The reference of Terra I used (right) is an official screenshot of Terra talking to Yen Sid. I just vectored it in black and white, using white lines to emphasize the edges and details. The red lines you see all over the Terra ref are lines I drew in for my own reference while vectoring.
The grass was from the RK manga page (the one on the right). I duplicated it several times, flipped and fitted them side by side, and in the final wallpaper, I puppet warped them to a curvy shape. The grass was the most tedious and boring part of the wall.
So there's the ref. I hope I can find the time to upload the wall soon!
EDIT: Full wall up! [link]