Garcia is their unofficial team counselor. She knows which cases will hit them hard.
For Reid, it's schizophrenia and senselessness. For Hotch, 'justified' killings – Hankel and Boyd Schuller come to mind. And child molestation – especially if they are Jack's age. For Morgan, it's teenage rape. JJ is heavy on child endangerment. For Rossi, it's more random. But Penelope anticipates, and somehow, she knows.
So on the plane home, Garcia will sometimes dig into the life of the criminal, and in the life of the killer's parents and siblings and children, just to find something that will make it appear as though what the murderer did was logical, in a way. Or she'll hack into medical records and tell Reid that the patient is doing alright, and not going around and killing people.
She'll bake cookies for Hotch that he can take home to Jack, and she'll cheer up Morgan in some way that only she can manage. She'll hug JJ and tell her that she's been to visit Henry and that he's alright, and she'll bring Rossi coffee in a pink cup and stay in the office until everyone but the two of them have left, and then she'll bring him another cup and say goodnight.
Sometimes, it physically pains Hotch to think about Penelope, sitting alone in her office, especially if the crime is streamed live. He knows how badly it hurts her, to be unable to do anything, and so he doesn't complain when Garcia calls him yet another ridiculous nickname. And if Morgan and Garcia chat for two minutes before getting to the point, he'll allow that, too. Because they have victims to safe, but they shouldn't lose themselves in the process.
And sometimes, when there is a case that hit her hard, he'll pick up something cute and cuddly from the airport, and he'll leave it in her office.
Penelope will find it and will bring him coffee, and they won't speak of it, but she'll walk with a little spring in her step, knowing that she hasn't been forgotten.
It's how they cope, and sometimes, Hotch is afraid of what will happen if Penelope would ever leave the team – be it because of an injury or a forced reassignment.
But she's here now, and when he looks through the window of his office and into the bullpen, and he sees her standing between Reid and Morgan, and all three of them are laughing even though the last case hit them all hard, he decides not to worry about that.
Instead, he'll bring her something cute and cuddly tomorrow, just so she knows she's appreciated, and it will remain alright for a little while longer.