Mel needs more love.
She actually did almost exist. Instead of the co-op bots ATLAS and P-Body, the co-op mode was supposed to include Chell and another test subject named Mel. This was later scrapped and turned into the co-op bots that we all know and love. But after hearing this, I took interest in poor little Mel. I drew her in the corner of a test chamber sitting all by herself, as if forgotten by everyone and abandoned by GLaDOS.
Why yes, I am obsessed with Portal.