Turns out that Caitlin was retroactively present at that mock trial the time Will screwed that princess or whatever she was. The one that kept buying him gem-encrusted hi-tops and ponies with jewels in their hair. So they kind of know each other.
Alicia: "Don't talk to named partners. Don't look them in the eye. Stop flirting with my boyfriend. You are already kind of a sore subject."
Caitlin: "Please, Mrs. Florrick, I am just a first-year associate looking to learn."
Alicia: "It's okay, I trust you. Fill out these forms."
Mean IT Nerds are always so mean! Insecurity becomes arrogance which takes the form of anger because the insecurity is about everything else in the world besides this one thing they are good at, which then becomes rage because they have to say everything at top volume due to never feeling heard, so they belittle you about this one thing because they feel like you are belittling them about all the other things that there are, just by existing, when really the truth is that they are simply irrelevant, because they're so mean all the time, and because they're only good at this one thing.
Look upon your future and weep, Grace Florrick.
Alicia: "Why are you being so mean to me in my own office?"
Mean IT Nerd: "Because I am sexually frustrated! DIAF!"
Alicia: "Could you get out of my office?"
Mean IT Nerd: "You don't know what the cloud is! And now you have wrecked your computer! BSOD!"
Alicia: "Zach, please come to Mommy's office and fix her computer. The IT guy is being really mean again for no real reason."
Eli: "Parker Posey, you are my ex-wife Vanessa."
Vanessa: "Eli, you are the gnome that tricked me into marrying you just for spinning all that straw into gold that time for me. We have a daughter."
Eli: "Will you please make China stop being mean to this kid rapist, Chen?"
Vanessa: "Yes. In return, you will go with me to meet a man named Kim Kesler who thinks that I can be a state Senator one day. I want you to meet him and see what a jackass he is, so that you will be my campaign chief. We will fight all day long."
Eli: "Sometimes I think we are still very much in love."
Vanessa: "Don't touch my track suit right now, Eli. I have to go back to jogging now."
Eli: "Good thing I stalked you to your jogging so that you could do this elaborate scheme on me without me knowing it! I wonder what would have happened if those boys hadn't murdered that girl and we never had this conversation."