I think given the conversation I'm having with
@Crowley about Al and Will already working together on some things, that would most likely be the best bet for my boy and "Roxie" having made acquaintance. Maybe she's around when Will goes to discuss a new project with Al or to pick something up, or vice versa, she happens to be tagging along when Al's making a drop off or something. If it's just a happenstance meeting like that, Will is going to pretty much absolutely ignore her, lol. But it'll be a good start so at least they'd know who the other was when the shit hits the fan, and then they can grow from there.
I don't think it'd be as likely that Will has met Aaron yet (that he knows of). He doesn't have a car (weak legs and all) so there'd be no need for a vehicle mechanic in his everyday life. It's possible that Aaron's expertise in electronics may have had him working on some design or other that Will would've been contracted to consult on, but practical machinery is more Will's specialty. Anything majorly electronic would probably be a different phase of the project that Will most likely would not have been as heavily involved in. When they do meet up after all the chaos though, I can see Aaron's, Will's, and Al's talents combining together to make for a pretty formidable team when it comes to building useful shit.
Will (excited): Aaron! Aaron! Hey Aaron!
Aaron: What?
Will: There's a dead camper over the hill. Go give it CPR or something and bring it over here.
Aaron: ....Why?
Will: Uhhhh, so Al and I can turn it into a tank. Duh. Go. Shoo. Chant to the car gods and make some magic happen. I need it.
(Random headcanons are a thing, btw. Don't mind me. When I do these things it helps me flush out my character's personality a bit more as a I go along.)