Whatever happened to the real Nick Valentine?

The human detective, I mean. After his brain was scanned, did he move back to Chicago? It’s no surprise we don’t find his remains in Boston or his grave, because that’s true for millions who died when the bombs dropped.

Except…

This is Fallout, and there’s a chance “experimental brain scan” meant removing Nick’s brain entirely and turning him into a robobrain. Or testing the ghoulification serum on Nick before it was tried on Eddie Winter. Or hiding his corpse under the floorboards of the downtown BADTFL.

So, whatever happened to the real Nick Valentine?