"You die that fast?"

"Eighty-three's not like an unusual age."

"It won't take me eighty-three Years."

"Okay. I mean, I'm already twenty-four."

"Still. It sounds like the hardest problem I've ever heard of but no problem's that hard."

"If you say so."

He finishes eating. "I should get to work, though."

Nod. "You need anything else today?"

"I don't think so. Are there situations where singing will get me in trouble? - I'm very quiet in the library."

"...be quiet in the library, yeah, and if people tell you to stop then stop, or if they look annoyed? Or psychic annoyed. Otherwise that's... just weird not actually bad, most places and times."

"Okay." 

"Have a good night."

"You too!"

And off goes Dylan and the library elf can return to the library.

It turns out that testimony from divinatory powers is not admissible unless those powers belong to people formally embedded in the justice system (i.e. Protectorate heroes). Dylan's translator guy hooks up Fëanáro with some projects he can do if he learns the following languages, most of which he can in fact learn by pestering exchange students enough. He becomes something of a library mascot when he's been living there a while and it has been generally determined that he is not threatening. People want to take pictures of him and like quizzing him on random topics ranging from fruit fly genetics to the Elf world. There is a general air of humoring him on the subject of the Elf world being a real thing and not something he made up the way Glaistig Uaine talks about fairies or Myrddin talks about being a wizard, but they can sure humor him on that. (Even after Dylan publishes his thesis, asserting that Quenya is in fact too elaborate to be some conlang.) Computers become more of a thing. Dylan shows Fëanáro the internet.

Behemoth acquires a sibling. The Protectorate mentions to Library Elf that he'd be useful for logistics at Endbringer fights and showing up does not constitute an agreement to do anything else. They have him do comms from five miles out.

Behemoth and Leviathan acquire a sister.

Library Elf can do the math. This world is not going to last long enough for him to read all the books in the library and understand all of the technology well enough to recreate it alone in Valinor; the world is not even going to last long enough for him to finish the work on mortality he's put six years of work into. 

He needs people who are not him to be able to make artifacts. He's been crowdsourcing some of the artifact design as programming projects he posts anonymously online, but that still leaves him the only person who can make stuff and this stupid horrible world is running out of time. 

He writes the PRT. He needs some really excellent programmers to design a program that does this absurdly convoluted and highly specific thing. With no imported libraries, and as few lines as possible please, and he'll do the part where it has to be in discrete self-contained blocks himself. He'll do whatever stupid heroes-and-villains-game favors they want, this is important.

They can put him in touch with the software Tinkers if he'll help them track down villains.

He thinks they are a stupid organization with stupid priorities and the idea of helping to get people arrested turns his stomach but they do not deserve to have their world eaten bite by bite by horrifying monsters. He helps. Sulkily. 

Then villains will be arrested and software Tinkers can be set on the project. Tinkers have weird working requirements and can't always explain their code and some of them are incompatible with the project, but some of them can help.

The Simurgh hits London. The Protectorate would like him to make a trip to Brockton Bay for power testing.

Some of the software tinkers have figured out in the space of weeks things he'd been working on for a year. He will run their stupid errand. 

He goes to Brockton Bay.

They tell him there's a would-be Ward who supposedly has a generalized defense against mental powers. Useful if true. They're testing her against lots of stuff. They want to know if he can read her, if he can send her stuff, if he has anything else that might be able to dent her.

She's a trembling sixteen-year old with a cracked helmet too big for her covering her face. He can't tell her mind is even there.

"Can't read her. At all. Can't even tell there's a person there keeping their thoughts private, which is what I'd be able to tell about people at home. I can try sending things - I'm going to try sending you things now -" are you okay -

"I don't hear anything," she says after a pause. "Did you do it yet -"

"Yeah I did. Huh."

"Is that everything -"

"I guess we could check if my memory necklace does anything for you?" He takes it off. "It gives me nearly-perfect recall but humans are worse at that to start with - we're refining it to try to get to actually-perfect -"