You could leave him with someone else, for a brief time, if you have anyone you feel he would be comfortable with. I am moderately certain, if his bond is anything like my pack bond-- and from what Lethid knows, it's actually stronger-- he'll still feel you existing, just not be able to tell where you are.

Or you could just wait and hope. But if it helps, I don't know if there are any other examples of someone making a bond like this with someone within the world, and then not bringing them back, when investigating. Only infiltrators seems to leave those bonds behind.