For building relationships:
* Hit it off: This idiom describes the instant connection between two people.
* Click: Similar to "hit it off," this suggests a natural and easy rapport.
* Get along like a house on fire: This indicates a very strong and positive relationship.
* Grow close: This emphasizes the gradual development of a strong bond.
For shared experiences:
* Go through the wringer together: This suggests bonding through shared hardship.
* See eye to eye: This implies agreement and understanding.
* Share a laugh: This refers to bonding through humor and shared joy.
For physical connection:
* Hold hands: This suggests a simple but meaningful physical connection.
* Cuddle up: This implies closeness and comfort.
The best idiom to use will depend on the specific context of the bonding experience.