Here's a quick doodle of Karezi with a crayon tool in SAI before work. I love these two. I realize Karkat and Nepeta would never happen so I'll go for this too.
Terezi's adorable in her own weird way too.
This actually reminds me slightly of the stuff Nepeta draws on her shipping wall actually. The one in her cave I mean.
Karkat, Terezi and Homestuck (c) Andrew Hussie