Of Twins and their Adventures

Prompt: Q has a twin sister, who's a freelance assassin (best in the world) and has no regard for self preservation. Can be Bondlock, or not. Pre-00Q and flirty fluff, please! - Jess Or in which there is a Z to cause havoc with Q, and the Holmes brothers are very protective of their little sister. 00Q banter and small Johnlock.