She's fairly certain that not a single person on her team could ever guess it of her. The Agent Emily Prentiss they see at work – that she shows them at work – is strong and reliable. She never blinks, never flinches in the face of her duty, and always meets it head on. And she definitely never ever cries.
When she first joined the BAU, she had so much to prove to everyone, including herself, but especially to Hotch. It was clear she wasn't wanted, so there was no way she was going to give them a reason to send her packing. And at any rate, she wasn't about to go discussing her 'feelings' with people she didn't know and didn't yet trust.
But after her first week at the BAU, her compartmentalizing skills were already being tested to the limit. How was she to pretend that she didn't care, that her heart didn't break for the victims, that she didn't wish to pummel the unsubs out of anger and disgust? All alone in Quantico where her acquaintances were few and her friends were zero, who was she supposed to talk to?
So after that very first week, it all began – of course, at the time she hadn't known that it would turn into a ritual that's now lasted over 5 years.
They've questioned her over the years, asking her on multiple occasions how can she be so emotionless and detached from all that they see and do. And of course she falls back on that ready-made excuse that she compartmentalizes better than most. But the truth of the matter is that she's not quite as jaded and hardened as she appears – as she likes to let them think she is.
The first night home after a case, the ritual began.
30 minutes, she told herself. She'd give herself 30 minutes to let the emotion out of the boxes that she'd shoved it into all week long. The fear, the sadness, the disbelief, the disgust, the anger, the disappointment, the hatred, the hopelessness, the desperation, the frustration, the anxiety – whatever feeling wanted to overwhelm her during the cases they'd worked on that week, she gave herself 30 minutes to actually feel it. And for that time frame she'd do whatever she needed to do to deal with it – whether that meant going through a box of tissues, gulping down a pint of ice cream, or finding the nearest gym to pound it out on a punching bag. But when the 30 minutes were up, she'd put her emotions back in their boxes to pretend they didn't exist until the next time she could restart the ritual. She never let herself go past the allotted time, too keen on maintaining her self-control to just let emotions completely rule her life for anything other than those 30 minutes.
She'd just never planned for what she would do if someone caught her in the middle of those 30 minutes of unleashing.