What makes two people truly compatible as friends?

Shared values (what matters to you both), similar communication style (how you process), mutual investment (both initiating), emotional safety (you can be vulnerable), and complementary strengths (you enhance each other). You don't need identical interests, but you need genuine respect and care.

Can two people with opposite personalities be good friends?

Yes, when each appreciates the other's difference as a strength. An introvert and extrovert can be best friends if the introvert appreciates the extrovert's social ease and the extrovert appreciates the introvert's depth. Opposite personality can create dynamic balance or constant friction—it depends on respect.

How do I know if a friendship is one-sided?

You initiate all hangouts. They take hours to respond to messages. You share deeply; they stay surface-level. You prioritize their life; they forget yours. One-sided friendships feel draining. Real compatibility is mutual: both people invest similarly, both initiate sometimes, both remember.