Their relationship is codependent, they depend on each other.

He and I share a lot of things.

She can speak both languages fluently.

He learned about the concept of synergism in theology class.

He has a rare synaesthesia where he hears sounds when he sees colors.

Their opinions have many common points.

All of these points are on the same line.

We hold a community listening session every Friday.

These two planes are coplanar.

I am very interested in natural science.