This is how I believe a Remus a Sirius got together and it does go up until book 7. Which means there is book moments too.
Year 1
James, Sirius and Peter all become friends at the start of term feast. (Well actually just Peter becomes they're friend but you get the point.) Remus doesn't befriend them until later that year but he is already friends with Lily. When they do become friends Remus is instantly charmed by Sirius.
Year 2
(Near end of year) James, Sirius and Peter find out about Remus' condition. Which of course we know that they still want to be his friend.
Year 4
Remus stars to develop a crush on Sirius but he of course he decides to keep it a secret. The others are woking on becoming Animagus.
Year 5 (I know a lot goes on this year, not my fault)
They have succeed in becoming Animagi. "THE PRANK" (After the Prank) Remus refuses to speak to Sirius or anyone else for that matter. At first Sirius was giving Remus time to himself but once about a week passes that changes. Sirius just isn't acting the same. So now James and Peter are telling Remus about what is going on with Sirius and that he should forgive him already. Soon enough Remus pretty much gives in and forgives Sirius. Sirius starts to realize that whoever he ended up dating just didn't give him the same feelings like he had when around Remus. Nothing much happens between the two except of the end of year kiss. I don't really know how that played out so you can decide.
That Summer
There is this sort of awkwardness between the two boys. James and Peter notice this though don't say anything. Kiss isn't brought up again.
Year 6
Sirius starts paying attention to this certain feelings he has for Remus. Things at times are still a little weird.(A few months into the year) Something tragic happens to Remus and I have sort of wanted to believe that his mom had died. So Sirius goes and comforts Remus. (A little more then less way through the year) The two are able to share their feelings with each other and their friends. James and Peter were happy for Remus and Sirius.
The two of them are living in Sirius' flat. Life is just amazing.
Time of the Order
Sometimes Remus would be gone for weeks at a time leaving Sirius alone (or vise versa). At times things get stressful since they could say much about what they were doing. Though they made the best of it.
Halloween and a Little While After
Remus is away the nigh James and Lily are killed. You can a imagine how Sirius took this. When Remus comes back he isn't to worried that Sirius isn't there and then he finds a copy of the Daily Prophet. This copy reports the Murder of his friends James and Lily. Sadness overpowers him and he almost doesn't look through that days Prophet. Though he does and what he sees doesn't help anything. It reports the death of the muggles and Peter Pettigrew. Also that Sirius was the one to do this and was sen to Azkaban. This is all to much for him and all he does is takes his things and leaves not looking back once.
The book pretty much explains everything, but I have one thing. Remus even after all of this, he is hesitant to forget everything just yet.
Sirius goes to Remus and pointlessly rambles. Remus of course takes Sirius back. I mean he can't say no to him.
They are living together at Number 12 Grimmauld Place (stated in the book). Their lives are like they were before. (In the Ministry) The death of Sirius is probably the worst thing that has happened to Remus. It feels as if this part of him is lost forever. (This is hard trying to explain how terrible this is)
HBP and DH
Yes Remus does end up with Tonks. Though I will say he did love her but it will never be the same love he had for Sirius. I also feel like Remus needs Tonks because without someone like her in his life, try to imagine what that result would be. So I may not like the pairing but it has it's benefits.
Possible After
Now no one but the dead can tell us if there is an afterlife and we might not know till our own dying days. Though in the Harry Potter series I sort of think there is. Just only because of the Resurrection Stone.

If you have any questions about the writing above (or even a comment) please ask. I'll try to answer if you put the question in a comment but if you want an instant answer please ask on my wall. Thanks for reading. Wolfstar love!