OK, so Sherlock. I love Sherlock, and since it seems like i may be the only one here still reading ARAH, let me help u out!
She is introduced in ARAH #281 when Hawk, Stalker and a newer Joe called Mongoose are on a mission with the "regular" army in Trucial Abysmia. CObra is helping rebels or something, I forget. Regina Allen leads an MP investigative unit that the Joes tag along with on a mission. During the mission thier convoy gets ambushed by these CObra rebels and one throws a grenade at Hawk. Sgt Allen grabs it and throws it clear, but it detonates and destroys her arm as she throws it. In recognition for saving him, as well as all the work she did during the ambush and the investigation leading up to it, he invites her into the Joes, where she officially gets the codename Sherlock. She wroks as an investigator, sort of like an NCIS (rthe TV Show) character but obviously on Cobra stuff. I really like her actually. I dont think we've seen her since the Skybound shift, which is a shame.
Fun fact: That same issue also introduces us to the GI joe JAG officer codenamed Caseload.