Kathy, according to Wikipedia Hotch is listed as Unit Chief for all seasons but 5. Gideon and Rossi are both listed as SSAs. So, Hotch is the team leader even when it seems that Gideon is in charge.

Here's the whole entry on Reid:

FBI BAU Supervisory Special Agent Dr. Spencer Reid Played by Matthew Gray Gubler, Doctor Reid is a genius who graduated from a Las Vegas public high school at age 12. He is almost always introduced as Dr. Reid, even as the others are introduced as S.S.A. 'blank'. This was explained by S.S.A. Hotchner in the first (pilot) episode that the reason why he gets called that by the other members of the team is to immediately create a respectable impression of Reid, deflecting judgments about his age. It has been revealed that he holds Doctorates in Mathematics, Chemistry, and Engineering, BAs in Psychology and Sociology, and is working on a BA in Philosophy. After being kidnapped by an un-sub in "Revelations", he is drugged with narcotic painkillers and held captive by a man with multiple personality disorder. The man sometimes believes he is his abusive father, the angel Raphael or himself. As a result, Reid becomes addicted to the painkiller Dilaudid but later cleans up after going to a series of addiction support meetings specifically for members of law enforcement. In season 4, he questions what his mother has told him, and goes to find out that his father abandoned the family after the mother has a breakdown at a crime scene. He is godfather to Jareau's son, Henry.

But in the pilot ep, Gideon was definitely a Unit Chief when he lost those six agents in Boston six months earlier. In that ep, Hotch is in a position to render judgment on his ability to function in the field, so I'm guessing he's either the new Unit Chief for Gideon's old team, was already a Unit Chief and brought in to take over Gideon's team when he went on medical leave after Boston, or was promoted from within the team.

And thanks for clearing up my confusion on his bachelor degrees. For some reason, I was thinking they were in physics and psychology, not psych and sociology.

On further reading, Gideon was the Unit Chief before his breakdown.

I guess you could look it up and read it all for yourself, too.

I'm gonna keep reading! I am so hooked, damnit!

I just wanted to be sure there was nothing in the canon to contradict that timeline I'd put together (other than my messing up the degrees).

I want to write a fic about how Gideon first met Reid and got him for the BAU, but I first have to figure out for myself if he recruited Reid or if Reid searched him out. That's the big question in my mind, because it'd be interesting to see who had the initiative, Gideon searching out a protegee, or Reid looking for a mentor, or maybe both.

that would be good, and I have no idea!

Oh, opening episode of Season 5 on CBS tonight!

Man, that was painful!

Especially because I went and spoiled myself for what comes later while reading Wikipedia today.

BTW, as far as I can recall, Reid actually joined the BAU at 21, from earlier comments. I think he turned 24 early in S1 and it was mentioned that he'd already been with the BAU for three years by that point?

And for anyone interested in CM fanfic I *cough* have been writing some to get myself unstuck from the other writing. I just finished one that I really enjoyed where Hotch writes a series of letters to the team. It's here: [link]

Oh, Barb, those letters are great! And the letter to Garcia reminded me that she did call him "Aaron" at least once very early in S1, as well as "honey" a few times before the "sirs" started. That makes me think that he had been promoted from within the team.

Thanks for the insight!

My mom is coming out for a family party on Labor Day weekend, and spending a few days with me. The last time she came out last fall, she got me hooked on NCIS. I think I'll exchange the favor and show her a few eps of CM off my dvr, starting with LDSK and Derailed--those should take care of it!