Somewhere secretly station deep in the Terminus System...
On the secret Space Station called Black Aegis I with heavy duty cloaking and jamming equipment, along with powerful weaponry and defenses to repel danger. Hopefully enough to fight off any Reaper's assault if ever found, but there several others like this one hidden in other Systems. This is just the primary HQ of the renown N7 Spec Ops, at least under the radar as the Alliance allowed them to run with their chosen title.
One of their Non-Human operatives, a Turian male with Biotic capabilities and talent. Along with tech know-how, making him a dangerous and skilled Sentinel of his