Which companion do you think has the saddest backstory?

I personally think that Lily's backstory is pretty depressing. Even though she's not my favorite companion, she's still pretty sweet. She's always stuck in a state of confusion, with muddled memories of her beloved grandchildren. What gets me is that she used to be a caring grandmother residing in Vault 17... until she was captured and dipped in some FEV. Losing her loved ones, she became alone, having to take orders from the Master until his death. What makes it even sadder is that she carries a holotape of her grandkids, which is the only thing that keeps her memories.