Tonight with your 5 to 8 year old
The prompt
“What's a game only you and I know how to play, or if there isn't one yet, what should it be?”
What to listen for
If they can name an existing just-the-two-of-you game or ritual, that's a strong, clear sign of a special bond they treasure, ask them why they like it so much and let them talk. If they want to invent one on the spot, lean into it fully; the act of creating something exclusive together is the connection itself, more than any resulting rules.
Notice if the game they describe involves closeness (tickles, whispering, a secret code) versus distance (racing, competing), both are bonding, just different flavors of it.
If they say "I don't know," suggest making one up right now together, the newness works just as well as an old favorite.
What this tells you
A private game that belongs only to the two of you is a strong sign of a bond they feel is truly theirs and safe.