They say blood is thicker than water.
The full saying is: The blood of the covenant is thicker than the water of the womb.
A covenant is a formal, solemn, and binding agreement, promise, or contract between parties, often carrying significant legal or spiritual weight.
In the sense of this saying I lean more towards the bond between friends, brothers not of the same family line.
I have a few of those.
Family that ain’t blood, blood that ain’t family.
S
Searching The South 