it is in the year that "Harry Potter and the Deathly Hallows Pt 1" took place

you are a former (defected) death eater, and have just taken an unforgivable vow with Dumbledore to never betray the Order. It is decided that you will live in the Burrow (Weasley residence) for the time being, as you currently do not have a place of residence.

you are sitting in the living room of 12 Grimmauld Place, chatting to Order members, when Molly Weasley comes to take you to the Burrow

when you walk into the Burrow with Molly, there are various reactions to your presence.

Arthur looks slightly startled, Ron doesn't know what's happening, Fred and George wear identical smirks, Bill's expression is unreadable, and Ginny gives you a warm smile