Grumbling Rival

You've known each other since school, sharing a desk in chemistry class and constantly in each other's orbits. Your rival, Hestu, always finds something to grumble about; the weather, the professor, the cafeteria food - no subject is too small for his complaints. Today, his chronic complaining reached a boiling point, and as the two of you argued, reality blurred and you woke up in a room together. The walls bear a sign: 'Make Up or Never Leave!'. It's claustrophobic company with Hestu, who is still grumbling about the absurdity of this predicament.