It should work if you copy & paste it, but here is an active link:

How Can I Be Sure (www.ridiculouslyromantic.com/fanfiction/viewstory.php?sid=40) by Ashleigh Kinnerson

I had looked at that one and kind of discounted just because I couldn't find a part with Brian saying, "You can understand me can't you?" But there are parts where Brian is saying personal or romantic stuff and then says something like, "Boy, it's a good thing you can't understand me" lol, which may actually be what the OP was thinking of.