Prime 3 is essentially before Metroid 2 and Super Metroid, which are kind of big parts in the frachise.
But really the last games I need to finish that I own of this franchise is Prime 3 and Other M. So I cannot yet fully throw my thoughts about Other M yet.
But I do think that Samus was showing a bit of instability during Fusion, an implication that she has some issues as a character out of Other M. Based on what I know she suffers from some sort of complex, likely connected to father figures, and an essential part of her relationship with Adam. A likely hood is that she has an Electra Complex, and if so I do not think of it as a huge downside of her character being ruined, but the one human flaw has gotten for having to live through some horrible experiences.
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Through dream I travel, at lantern's call
To consume the flames of a kingdom's fall