I asked at check in at for a friend on a separate ticket, it was a pretty empty flight, and the CSR gave him the aisle across from me.

I went into it with zero expectation of it happening, so I had noting to lose if she wouldn't.

*strictly guessing*: there are a ton of variables to this request: Flight length, load, and available seats may factor in the decision as well.

Side note, if you don't have success getting him moved up and really want to sit with him, I'm sure his companion in E- would be happy to switch with you.