High friction, high payoff. Focus on mutual respect growing from rivalry.
A moment where their initial prejudice about the other person is proven wrong. High friction, high payoff
One character must choose between their personal goal and the relationship. a shared mission
Forced cooperation (the "One Bed" trope, a shared mission, or a workplace project) forces them to interact. High friction, high payoff
A moment of unexpected competence, vulnerability, or wit that makes the audience (and the characters) take notice. Phase II: The Push and Pull