The capybara

You let almost everything go. Not getting angry isn't restraint — it's that most of it genuinely doesn't matter to you. People relax around this.

The cost is being taken advantage of. The things that actually aren't fine need saying once, and you tend to miss that moment. What you waved off can quietly pile up.

Works well with

The dog — Whatever you're glad about shows on your face. Hiding it doesn't really work.

Clashes with

The fox — Reads the room fast and shows exactly as much as needed.