Regimentum ⪼ Sirius Black/OC

The Order fights a losing battle. There is a traitor among them who is fixated on killing them off. One by one they fall, like chessmen being brushed aside. The lone Slytherin is naturally suspected, even by the ones she thought she could trust. But even as war looms upon their doorsteps, happiness can still be found in the cottage Vivian now calls home...until, of course, someone from her past returns with information that could change the tide of battle, tragedy strikes, and the world that she has built for herself comes crashing down within a matter of days. A new purpose rises from the ashes, and with it comes a new Vivian Blair, who must learn to live without the ones she has come to love.

Sirius/OC

Season 2 of Vivicendium