Poseidon, I feel, had friends all over Olympus and the sea.
Mainly his wife, Amphitrite, and their son Triton. Also Poseidon's brother Zeus.
Poseidon's most loyal ally and friend was Delphinus (Dolphin). Delphinus was that one that helped find Amphitrite and convince her of the love Poseidon had for her.
the function of Poseidons temple was for Poseidons honor.
Rhea.
cronus
Cronus and Rhea
Triton
Neptune
Rhea.
a trident
He doesn't had friends
In myths, he does not have one.
you don't
Give it back to Poseidon.