In Fallout 4 it was your baby.
I think it might be either wife or mother, we're getting kinda out of options here.
Fallout 5 will go back out west. MARK MY WORDS
you will choose if you want to rescue the remnants of the Enclave, Help the NCR or maybe even help the legion
I CANT WAIT FOR THE WEST TO COME BACK TO FALLOUT- hopefully in a new, and beautiful engine
You can speculate about future Fallout games here: http://www.gamesas.com/topic/1539832-fallout-5-speculation-ideas-suggestions/