Novel site:
https://www.baka-tsuki.org/project/index.php?title=Maru-MA
and if you want to meet people who like kkm (and many also like yuuram), check the tumblr tag :
https://www.tumblr.com/tagged/kyou-kara-maou
It's because of those two that I discovered the world of shounen-ai and yaoi--had no idea what they were before this, then I watched the anime and thought, hmm, I'd kinda like to see more of this, and then BAM!!! All of a sudden I read my first yaoi, had NO IDEA what I was getting into, and was a bit traumatized, but no regrets! Still wish Yuuram would be more cannon tho...*sigh*
If you read the original material (novel and stories written by the author), yuuram is canon. In the manga adaptation they're pretty canon too. Maybe not in the anime though.
There's always that one series that turns girls into fujoshis... this is a nice starter one.

Hi I've been a Yuuram fan ever since I watched the anime. And I really felt sad when it seemed that Yuuri doesn't love Wolfram as more than friends. BUtI think I will want to read the novels. Can you please tell me where I could read the complete novels? Thank you!