One character is cynical; the other is optimistic. They balance each other's extremes.
Before the first meeting, you need to establish why these two characters need each other (even if they don't know it). One character is cynical; the other is optimistic
High comfort level, but the fear of losing the friendship creates the stakes. One character is cynical
Chemistry isn't just physical attraction; it’s Banter: Matching each other's wit or communication style. a shared mission
Forced cooperation (the "One Bed" trope, a shared mission, or a workplace project) forces them to interact.