The Toxic Team: Terminator approach
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Remember that simple discussion that ended up a massive fight? Just because that one person thrown a tantrum, making it clear it will either be their way, or they will make everyone regret? That's the Terminator approach.
Some people will feel personally obliged to win every argument. Their ultimate goal: make their way, whatever the topic, whatever the cost, no prisoners taken. It's very hard to work with such person, because they make it feel like walking on egg shells—any divergence from their personal vision causes a nuclear reaction. Moreover it might be difficult to point out their behavior, because the Terminator is convinced they are right (this seems to be a common trait of toxic teammates).
Tackling the Terminator is not easy. First step is being assertive: "I hear your idea, and I noted it, but let's not skip to conclusions". Sometimes it helps to write down the ideas, to make it clear every idea was heard, and will be considered. Second step may be the change of conversation, switching to another topic. Be calm, be kind, do not let the Terminator to weaponize your own emotions and strike you. Make it clear that tantrums will not be tolerated, and instead you're very open to hear a constructive, fact-based approach.
Remember that kindness goes a long way, and the Terminator might not be fully aware of their disruptive behavior. Being a supportive teammate will help you with staying calm, and also help them grow.