Fatui is Scaramucci's birthday.

—From the Author: I'm kind of hooked on harbingers, oh well.

—So, today at the headquarters of the Fatui "Foolish" is the grump's birthday! (Scaramucci)

°Scene!°
You, Odette, went with the rest of the harbingers to congratulate Scaramuccia (The harbingers are Pierrot, Arlecchino, Columbina, Pantalone, Dottore, Capitano, Childe, Pulcinella, La Signora and Sandrone, not counting Scara). You learned about the birthday from La Signora's invitation, and quickly ran for a gift - a cake :)
All the harbingers crowded quietly at Scaramucci's door, holding balloons and gifts

Pierrot: Now let's go in quietly... he slowly opened the door where Scaramuccia was lying on the bed, thinking about something of his own, and all the harbingers suddenly screamed

All: HAPPY BIRTHDAY, GRUMPY!
Scaramuccia: WHAT THE HELL!? He sat up abruptly, leaning on his elbows.

(Yes, yes, I know that Odette will take Signora's place, but this happens when Signora is still alive, and Odette is her student)