I’d love to, but honestly, I’m not normally a big fan of crossovers and read things so long ago that all I can really recommend are superphantom fics. haha. But, if that’s okay with you, I’ll list some of my faves (although it’s so hard narrowing it down any because they’re all so fabulous! and if you want to see every one that’s ever been written, go here and here and I’m working on part three):
BOY HOWDY HAVE YOU COME TO THE RIGHT PLACE, FRIEND.
these are what i consider the highlights of the Armando Muñoz/Alex Summers tag on AO3. i haven’t dug my way through the kink meme yet, but this should hold you over for a while, so have at it. Remember to read the fic tags so that you can avoid any triggers you need to, and have fun!
born into trouble as the sparks fly upward — this is a post-vietnam fic where alex is dealing with ptsd and the after effects of that war, and armando may or may not be alive again. please heed all the trigger warnings.
Come Back to Me — armando wakes up in the rubble of the cia compound, and there are feelings. essentially the obvious prelude to the usual reunion fic.
Snail Mail — probably the most well know a/a fic, but still a great one. alex works for erik, who is married to charles. armando is charles’s t.a. meet cute for the boys because charles and erik thrive on arguing with each other.
Molten middle — an armando comes back fic. really sweet, with some nice alex&hank interaction on the side.
tell them i ain’t coming back — the firefly au. really good, and you can definitely interpret armando as being somewhere on the aro and/or ace spectrums with this fic, which was really nice.