I finally made a 'run' up the coast to Longneck Lukowski's Cannery, which some poor guy with Delhi belly had been complaining about.
Cleaned it out. (Pleased to get a bunch of Radstag meat.)

I was then fairly heavily loaded. Tons of good loot in the cannery. I wanted to maybe swing just a bit north and check out the Kingsport Lighthouse, but should I?
Thinking about what to do, I'm up on the roof of the Cannery gazing north. Something moving down there near the beach...?
So I put VATS on it with my long weapon, to see what it was - clearly it was humanoid (not a Mirelurk) but it was all alone, and just standing there.

Imagine my surprise at recognizing Mr. Lorenzo Cabot himself! OMG! Long way from Cabot House...
So I get down there and he says "Ahhh, hello old friend. I'm so pleased to be out and about, exploring this new world."
And I see he's surrounded by dead Feral Ghouls, heheh.
Anyway, I got some unexpected dialog options. "You murdered them?" and this sort of thing... huh?
So I look closer and I see the deceased are not ferals - they're just ghouls (settlers).
Nevertheless I was real polite to Lorenzo! He is of course a beast, with that ancient headpiece and nutty gun of his. But he likes me.
I wasn't going to freak out on him over three dead ghoul settlers, y'know? I need a steady source of his Mysterious Serum.

At this point I was half way to the lighthouse, so like a dummy I head a bit closer and BOOM - I get swamped with those nutty Atom guys, and they're just hammerin' me with their Gamma Guns or whatever they are...
Yeesh. I'm thinking Lorenzo will help, but no, he's just standing there.

The battle was long and nasty. Those Atom guys can be tough, and there were a lot of them...
At some point I see Cabot wading in to the fight, and I say to myself "now these Atom guys are toast."
I finally extinguished the last one. They are all over, down on the shoreline, in the boathouse, on a boat, etc.
Including the big boss Legendary Atom Minister at the top of the Lighthouse.

So I'm looking around for Lorenzo Cabot and I see something twinkling in the grass...
Oh no - it's Cabot and he's very dead! Buddy apparently sniped him from the top of the lighthouse!
Good Lord. And I can't even carry all this stuff anyway... whatta mess.
Anyway, looks like no more Mysterious Serum for me!
And if I had just gone back to Home Plate from the bloody cannery, it could have all been different.

Oh, I hate those Atom guys now.
So what do you guys think - would you have reloaded a save?
I am carrying six vials of precious Mysterious Serum, and I did not.

Just another day in the commonwealth. Loot him for what he's got and leave him for the rats.

LOL now that's bad luck, I say! I didn't let him live the first time around and never bothered with the Cabot quest during my 2nd play-through. I might do the quest with my 3rd character, but still not sure if I'll release "the beast". The serum isn't that vital to my survival, seriously. I think I may have used a whole of 2 vials from the 6 or 8 you get during the quest.

If you went through all the trouble to get a steady supply of the serum, maybe it would be worth it for you, to load an earlier save... depending on how far back you saved though.

I also hate the Atom guys with a passion!!! LOL

Thanks for comments!
Hey I guess Cabot House, in all its pre-war splendor, is completely unoccupied now...?

I have the save from on top of the cannery, before I unwittingly and foolishly rousted all the Children of Atom.
But I have six vials of the Serum, and the guy was a menace - maybe it's better to leave him dead?

Bottom line for me is, I can't really use Cabot House anyway (no workshop).
And going back ten minutes to before it happened, I'd have three or four hundred more plasma cells upon returning home!
But no lighthouse...
Y'know, maybe I'll leave the nasty old fooker dead.
And I've never had my own lighthouse before, heheh...

Has anyone ever saved old man Lorenzo before, and then encountered him out walking about?
Because I tell ya, that was completely unexpected.
The guy is like 500 years old and I felt kinda bad (like his death was my fault).

You know, I might reload and do it over - but this time make certain Lorenzo lives!
(Hey that's like 'Option 3' and never occurred to me last night.)
I can keep him alive no problem, but I just didn't think I'd ever have to...
Anyway, it was a shocking reminder that no one in the game is truly indestructible.