I want to use a phrase that takes the form of possession. It may be a matter of an apostrophe with s or a usage of a possessive pronoun, I suppose.
What I want the phrase to mean and indicate is that there are two individuals whom I want to talk about the life of only one of them instantaneously.
The sentence (not the original one):
They were always together until destiny took away ______ (one's life of them?).
I want the phrase to be a substitute of the life of one of them.
I would also like to know if there are other ways of stating the phrase in a shortened form.