I started out sketching the misfitted couple of true detectives first. These are my final sketches where I tried to capture their facial features in a cartoon-ish style. These were preceded by several other attempts.

Marty vectorized in Illustrator.

Rust vectorized in Illustrator. I wonder what the man would've to say on that?

In the end I added them both together in a wallpaper, after I added some shading and slight texturing. The idea is to create a complete True Detective poster in this cartoonish style, but for now, the wallpaper'll have to do.