I came from a base of acting. In college, I studied acting and directing for film. Later, I did a lot of musical theatre training along with a tour here and there. Though musical has a tendency to be bigger acting, I know a little about realistic scenes and when it comes to improv, I feel like "realistic" scenework is the consistent improv mystery.
We all go to shows where there is almost never a slice of life scene. You are more likely to find those scenes in two-prov where efficiency doesn't necessarily have to happen. The best improvisers in the city do the same things we all do, pull themselves out of scenes, make big character choices that normal people wouldn't, and call out things that no one realistically would call out. For example, the concept of yes and ing isn't realistic, it's a tool.
So, the big question is, how do we start behaving more realistically in scenes without just having it be a boring scene. Here are the notes that I've heard from teachers when it comes to grounding work.
1) React honestly.
2) Know how you feel about people and ideas.
3) Do object work to feel the space.
Here are the notes that contradict those notes.
1) Find the game.
2) Follow the fun.
3) Yes And.
I think of it as two different ideas. The ACTOR and the IMPROVISER, the actor immerses and feels and figures the situation out. The improviser is a point of view above yourself. An actor doesn't have rules, an actor will do a transaction scene, conflict scene, or nothing at all. An improviser is a little harder, the improviser has to figure out the scene through the rules and guidelines put forth.
Alright here is my take on realistic scenework. You are two improvisers in a scene. Whoever starts the scene, lays a single road, you have your road which exists and is parallel but it is a little behind the road that is put out there. You're job is to get on the same page quickly. A good support improviser will take the little he has and manipulate it to run parallel with the initiator, a good initiator will slow down a little bit to let the support catch up.
The moment we have a feel for the scene and who we are to each other, which doesn't have to have ANY words, we are on the same page. If someone initiates with a voice or a mannerism or something weird, you ground it by acknowledging that this person is FAMILIAR and FRIENDLY. Here is why it is cut and dried, if you are unfamiliar, anything they do is going to elicit a WHY, which means they are crazy. The more matter of fact you take it the better. By Friendly, you don't want to make the scene about getting a person to stop or be different than they are. Often times, people think that reacting honestly is calling out the weird thing. If someone walks with a limp, an unfamiliar person may want to call it a doctor visit or a person getting out of bed when they shouldn't. These EXPLAIN the situation but they STALL the scene because it is not about the relationship it is requiring a WHY.
Now what if a problem is initiated, a WHY. Why did you take my stapler? Well, first off that's an improv guideline that you are bending. But, this happens a lot. The more weight you give that initiation, the harder it will be. You are familiar and friendly so you'll probably apologize and give them back the stapler and possibly yes-and the reason why he has accused you, and that's not, "What's wrong" because that's worse. You have to say SOMETHING, "Here ya go. Sorry. Listen, I know you're stressed lately because of all the lay offs. You've totally got the job man."
What about a crazy idea? A person comes out and starts doing something crazy with their hands. If this doesn't become a group game, then you go back to Familiar and Friendly. Familiar may imply matching. The more you don't call out or make the action weird, the more interesting it'll be and the more grounded it will feel.
Familiar and Friendly. Imagine taking any weird initiation, and I say weird as in just not normal not judging as bad, and making it wrong or weird or have to be explained. That is the WORST. You are stopping the road, telling your partner to come back and explain why you paved it this way.
Here's an interesting example that I did recently. My partner initiates by bringing in a body or something. I have this feel that it is almost wrong and I'm in a position of authority so I call it as I'm a father and my son just brought in a deer the day before we went hunting. I am familiar and I am friendly, but the BASE is you did something wrong. In turn, it was a funny scene but it LAGGED because I had to be a father who was okay but not okay with it. The moment I was okay with it and said, "Well, lets skin it and learn something", the scene blasted off. Try this, SMILE. There is NOTHING wrong.
If someone says, "I just killed someone,dad!", then you can go crazy honest and think about how do I solve this or SMILE and give him a hug. "You're gonna learn so much about yourself after this moment. My son is going to grow up."
In conclusion, try not to stall the scene and think that something is wrong. Know who the person is and LIKE them. Even if they are complete dicks to you in the initiation, you have to like them a little because you are going to have a scene with them and not leave. I believe the grounding comes from the fact that you like the other person and that this is an everyday thing and that NOTHING is crazy. Even if it is crazy, it's not. I'll test it in class and see if it works out.