I think all of them in one way or another suffer from PTSD, Garcia, Reid, JJ as examples. Garica was shot on her own door step, Reid torchered and drugs, JJ having to shoot those dogs and all that, that happened with Reid. It's how they handle it. Hotch's PTSD could be long standing, such as when that explosion did some damage to his hearing.
As to Emily and Hotch, first may I add I hope not, and second I don't think so, I think their relationship is just that of mutual respect for each other, as explained above. But I think in someways, Hotch is still trying to get past his divorce and deal with the job. For him to get into a relationship with one of his agents would put a strain on the team imo. And he wouldn't want to lose Emily as a team member, or jepordize the team because if they got into a romantic relationship someone him or her would have to go, and with Emily she trusts him but that trust like with everyone else only goes so far.
The one thing I like about this team is they are more family, Morgan flirts with Garcia but neither takes it seriously. Reid took JJ to a ballgame, but that wasn't serious. It's all about completing each other and complimenting each other. They may have their outside families, but they are family on the job, they are playful and joking, caring and kind, and know that they can count on each other in that time no matter what. Emily when she confronted Reid about how he was acting, and Reid lashed out at her that she hadn't been there long enough to know him. She didn't flinch she didn't spit, she let it go but gave off the vibe that Reid picked up imo. Hotch gave that speach to Struss about his team that is family style.
Incase some are wondering what speech I am referring to this is the one. (2x23 "No Way out (2): The Evilution of Frank)
Hotchner: My team? Let me tell you about my team.
Agent Morgan fought to protect his identity from the very people who could save him. Why? Because trust has to be earned, and there are very few people he truly trusts.
Reid’s intellect is a shield which protects him from his emotions and, at the moment, his shield is under repair.
Prentiss overcompensates because she doesn’t yet feel she’s a part of the team. She needn’t worry.
Every day, Agent Jareau fields dozens of requests for our team and every night she goes home hoping she’s made the right choices.
Garcia fills her office with figurines and color to remind herself to smile as the horror fills her screens.
And Agent Gideon in many ways is damned by his profound knowledge of others, which is why he shares so little of himself yet he pours his heart into every case we handle.
I stand by my actions and I stand by my team, and if you think that you can find a better person for the job, good luck.