Oh..., Oh God. (Where is that from anyway?)
It's the last boss from fallout 1, you can either shoot him up or reason with him an tell him that his plan is flawed because mutants aren't potent therefore they can't reproduce.
Either way, I seriously recommend you pick up a copy of fallout 1 before technology advances(it's 14 years old) it was one of my first PC games and it is still to this day, one of my all time favorites. there is also a great community of older fallout fans who would love to here your opinion on their favorite RPG.
You should also use a DOS emulator and play Wasteland because that's the game that inspired the genre of Post Apoc RPG's. It's cool because the second game is comining out really soon(It's been in devolpment for a year or two).