Remus is waiting for Sirius to come home, and writes him a letter.
Remus had always been waiting, for everything. It would not be a lie if he said that his entire life had been one long wait.
At first, Remus thought Sirius left him. Actually, he simply missed him.
The only thing Remus was sure of, conserning a kiss, was that Sirius would definately not push him away, or attempt to hurry off to save the world - or The Boy Who Lived, for that matter.