I think people are a bit too quick to rule out the possibility that Varis wants an alliance. After all the Scions have resources (such as the WoL) that he doesn't. Even Regula made a point of people with the echo being important. That doesn't mean he is trustworthy or his endgame co-insides with ours but he seems to see the Eikons as a major threat. A couple of border provinces are probably low on his list of things that are important compared to that. Its also worth noting that the emissary is here investigating if an alliance is feasible. There is no way the Emperor would come to a hostile country in person.

I think this is probably going to be the beginnings of our 'in' when it comes to traveling to Garlemald. A strong dose of distrust all around is probably for the best because we will almost certainly be heading into a political quagmire. However I think that in this case Varis is actually serious in seeking an alliance. He might stab us in the back later if he feels it is in the interests of Garlemald to do so but for now I think he desires our resources. After all do remember he could have easily let Zenos of the leash at any time. If Zenos had permission to invade Eorzea we quite likely would have had a very different outcome to the war.