Derek Smalls (played by Harry Shearer) is the bassist for the fictional British heavy metal band Spinal Tap. He considers himself as being the "lukewarm water" between Nigel and David's fire and ice, or the "glue of the band."
There are roughly one-sh*t billion tropes so PLEASE look through them before adding one. Otherwise add what you like. ADDITION: PLEASE read through the trope description provided before submitting something. It's not a huge deal but too often people submit characters that don't fit just because they misinterpreted the title...