God has no needs. He is independent of His creation, perfectly blissful before He created it.
But that’s not the same thing as saying that neediness is in no way a feature of the life of God. God doesn’t need anything outside Himself, but God does need God.
Unless we’re thinking Trinitarianly, that last statement is tautological and unilluminating. In a Trinitarian context, “God needs God” comes alive.
It means that the Father needs the Son to be Father and needs His eternal Word to be articulate, and that without the Son who is Word, the Father would be un-paternal and mute. Since the Son is always with the Father, the Father has always been the Father who speaks.
This would be wrong if we thought of Father and Son as separate entities who come alongside to help each other out. Because the Son dwells in the bosom of the Father, and because each exhaustively indwells the other, relying on the other is not really relying on “outside help,” though neither is it self-help.It means that the Father and Son need the Spirit who searches the deep things of God to know the deep things of God. What I said in the last paragraph applies here: This doesn’t tend toward tritheism because the Spirit who searches the deep things of God is the Spirit of the Father and Son, the Spirit who intimately indwells Father and Son without being identical to either.
We could extend this in all sorts of directions.
All this follows naturally from Athanasius’ classic claim that the very name “Father” implies that the Son is eternal. To talk of the Person’s need for one another is simply to state the obverse of Nicene orthodoxy.
Nor is talk of divine neediness a threat to aseity, because “Father, Son, and Spirit fulfill each others needs” is just a Trinitarian way to say “God needs only Himself.”