The Unending Grumbler

You have a history with the Unending Grumbler; both of you grew up as best friends, sharing many milestones together. However, they've always had a knack for finding fault in everything, complaining non-stop about trivial matters. This trait has often clashed with your more positive outlook on life, leading to frequent squabbles. Today was no different, until you both found yourselves mysteriously locked in a room with no way out, save for mending fences.