I'm not even sure how I stumbled upon R/T...I just remember thinking I was being weird.

But it seems to be a fairly plausible relationship..I mean, after all, they must both have been close to Sirius, and I'm sure his death brought them closer together. And they're two of the few 'younger' people in the Order, so it makes sense that they would have a little more in common with each other than with some other people.