After Samus became infected by the X, her immune system was helpless to stop it as it slowly took over her armor and body, leaving her to have her once-great power armor surgically removed, and we're it not for the Metroid Vaccine created from cells of the baby Metroid, she would have likely died, or worse, become a threat to the galaxy as a slave to the X...

But what if the Vaccine didn't fully work?
Come and ponder, for a moment, what the outcome would be if the vaccine created to save Samus and eradicate the X from her system, merely halted its progress, leaving her infused with the mutations in her power suit, and the abnormal powers to not only drain the power of the X given by her Metroid genes, but also the ability to amalgamate and copy the powers of some of her Foes?

Her adventure on the BSL would likely be different, yet very similar to the one that we as fans know, but what about her fateful trip to planet ZDR? Something entirely new and unpredictable may have happened...
Wouldn't you agree?