So basically Tybalt was bluffing all along. There wasn't a fire, and nobody saw the mc setting the sprinkler system because the mc didn't.
But going back to the deal between Jill & Tybalt, what we saw:
Tybalt: "Watermelon?"
Jill: "None for me, thanks."
Tybalt: "*Schlurp suck*"
Jill: "What exactly happened last night?"
Tybalt: "Oh, there's time to discuss that later."
Tybalt: "How have you been? How was your weekend?"
Jill: "I feel this is more important to talk about right now."
Tybalt: "I saw that you made pancakes with Bella. Do you like pancakes?"
Jill: "Tybalt..."
Tybalt: "*Schlurp munch*"
Tybalt: "If you insist."
Tybalt: "As you know, there was a fire in the mansion."
Tybalt: "As soon as the sprinkler system started, I rushed to locate it and put it out with my jacket."
Tybalt: "My Italian tailored one, you know, the one that daddy bought for me. It's completely ravaged."
Jill: "Where was the fire?"
Tybalt: "You don't need to know that. I don't want you to feel unsafe."
Tybalt: "But what you should know is that it ruined the party and the chance for many of us to get closer to the guests."
Tybalt: "I think it's safe to say that it impacted all of our futures."
Jill: "I'm very sorry to hear that, I know how much you've been looking forward to it."
Tybalt: "Yes, it's tragic, indeed."
Tybalt: "And what you also should know is that your "friend" caused all of it."
Jill: "Who do you mean?"
Tybalt: "You know very well who I mean. The one you've been off gallivanting with."
Tybalt: "It's not the first time I caught him trespassing."
Tybalt: "And I'm aware, you said he's welcome here, but I think you should reconsider."
Tybalt: "When confronted, he even resorted to physical violence!"
Tybalt: "Luckily for me, he's very weak and I have a strong jaw. I barely felt his punch, but that's not what matters."
Tybalt: "We can't have a person like him on our property, ruining our parties and our futures."
Tybalt: "And what about your future, Jill? Will you let him ruin that as well?"
Tybalt: "He's a horrible human being. He's an arsonist, a trespasser and a big bully."
Tybalt: "He stood right in front of me and called me horrible names!"
Jill: "How can you be sure it was he who started the fire? Did anyone see him do it?"
Tybalt: "Gordon recognized him from the party. He was indeed in there with all of us."
Tybalt: "Probably looking for the best way to do it. Ask Gordon and the others, they will concur."
Jill: "But that's not proof."
Jill: "I think you've got it all wrong. He's not like that."
Tybalt: "No, Jill. You're the one who's got it all wrong. But I don't blame you..."
Tybalt: "I suspect that he's a master of manipulation."
Jill: "Ridiculous. This doesn't match anything I saw from him."
Tybalt: "He punched me, Jill! There are multiple witnesses!"
Tybalt: "There are multiple witnesses, Jill!"
Tybalt: "He threw eggs at us, too, when we chased him off!"
Tybalt: "The only logical way to combat this is to press charges."
Jill: "No, Tybalt! Don't you dare do that to him."
Tybalt: "See, I knew you would side with him and that's why I've been holding back."
Tybalt: "All because of you."
Jill: "And I thank you for it. You're doing the right thing."
Tybalt: "But I talked to Trent and he's not as noble as I am. He says we should press charges."
Jill: "Trent said that?"
Tybalt: "Yes, he's adamant and very petty. So extremely petty! I was shocked!"
Jill: "Let me talk to Trent, I'm sure we can come to an understanding without lawsuits."
Tybalt: "I can handle Trent for you. He'll listen to reason, if I really explain it to him."
Tybalt: "But...I've made so many sacrifices now."
Tybalt: "The ruined suit, not pressing charges, allowing him to trespass for you, being bullied..."
Tybalt: "...being assaulted and having to take it like a man..."
Tybalt: "I feel unappreciated."
Jill: "You're not unappreciated. I appreciate it very much."
Tybalt: "Well, I can make sure we drop all of it. For you."
Tybalt: "No lawsuits, no police reports, no nothing..."
Tybalt: "And, in return, maybe you could do a few things that are right, for me?"
Jill: "Yes, of course. What are they?"
and the scene ends. But what could have easily followed is:
Tybalt: "Jill, I'm sure you know how I feel about you."
Jill: "*Sigh* Yes Tybalt, I have an idea."
Tybalt: "Then would it be too much to ask for you to go on a date with me?"
Jill: "Tybalt..."
Tybalt: "Here me out. Nothing dishonourable. Just a casual stroll through the mall. Or a friendly game of tennis. Or perhaps, yes perhaps an exquisite dinner, just the two of us."
Jill: "Fine Tybalt, I can do that."
Tybalt: "Three dates! Well this is a grand outcome!"
Jill: "Wait! I didn't... Fine... But just three dates."
Tybalt: "Of course! Three dates is all we require!"
Tybalt: "Are you sure you don't want to partake? This watermelon is extremely juicy!"