For this to make any sense, you ought to read the previous chapter carefully.

(A few moment's earlier) *Seto Kaiba
If I didn't act fast, Pegasus would kill me. Although this was not the first time someone had held a gun to my head, it was defiantly the first time I was scared. "Get your hands up Kaiba. I don't want any tricks from you. My guards will soon bring Natalia back and she will watch as I kill you." He said with a laugh.
I glared for a moment then grabbed the barrel of the gun, pulling it away from Pegasus but not being able to grab it for myself. I jumped out of the stairwell, in case he thought about pushing me down it. He spun around to face me and I glared at him. "Did you really think you were going to get away with that Pegasus?" I said angrily.
Pegasus chuckled and ordered his guard to grab me. I had seen this coming so I grabbed the guard's wrist and threw him over my shoulder. Soon after, I realized that this had been a distraction. Pegasus was headed for the gun.
I jumped him from behind, taking him down. His guards had all gone after Yugi and Natalia so I no longer had them to worry about.
I struggled with Pegasus on the floor, both of us trying to get the gun but neither of us succeeding. Eventually, I managed to get my hands on the gun even though Pegasus was on top of me, holding me down. I fired the entire magazine into his chest.

*Mokuba Kaiba
"We are not leaving this roof until my brother is in the helicopter!" I yelled to the pilot. He simply nodded. I watched the elevator for my brother or someone else I knew. After a minuet or so, Yugi and some woman I didn't recognize stepped out of the elevator. She was in bad shape. Yugi was almost carrying her. I jumped out of the helicopter to go help them. "Mokuba," Yugi called as I ran over to them, "I don't know where your bother is. We need to leave now. It's not safe."
I looked at him like he was crazy. There was no way I would leave without my brother. "Yugi. I can't leave yet. You take the other helicopter. I'll wait for Seto."
"No Mokuba. You need to leave now. It isn't safe here." Yugi argued as he helped the woman into the helicopter.
I sighed and ran back to the other helicopter and jumped in. "Take off but don't go anywhere until I tell you too. We have to wait for my brother." I said.
"Yes sir Mr. Kibia," The pilot replied as the helicopter rose off the ground.

*Seto Kaiba
I pushed the body of Pegasus off myself. I was covered in his blood and some of my own from being thrown on the ground. I wiped off my mouth and glared at him. I knew the guards would soon be coming back so I had to get out of there, and fast.
I ran towards the elevator and from the looks of it, the guards had just gone up. There was only one standing at the bottom and I could easily take one on. I had already done so many times. I pointed the gun I had taken from Pegasus and pointed it at the guard. The guard backed down as the elevator door opened. I stepped into the elevator and continued to point the gun at the guard until the door was fully closed.
I fell back against the wall of the elevator with a sigh. I looked at my blood stained clothing. I had killed Pegasus. How was I going to explain this one? I thought to myself as the elevator reached the roof.
As I had expected, the guards were waiting for me. I held the empty gun up to them, hoping they would buy it. To my surprise, they did. I looked around for the helicopter that was supposed to be here. I couldn't find it anywhere! It was already gone! "Shit," I muttered under my breath.

*Mokuba Kaiba
"There he is! There's Seto! Land this Helicopter now!" I yelled to the pilot.
"I can't sir. It's too dangerous." The pilot responded.
I looked around for another option to landing the helicopter because I knew the pilot was right. I would be suicide to land the thing. "Fly above him and keep it steady." I commanded and the pilot did as I asked.
I dropped the latter out of the helicopter, letting it hang above Seto. "Grab on!" I yelled to him. He looked up and gave a motion to lower it a bit more. I commanded the pilot to lower the chopper a bit so my brother could grab on. As soon as he had a grip on the ladder, I instructed the pilot to take off again.
I watched my brother carefully, to make sure he didn't fall off. What I didn't check for, was the guards. They had started shooting at him and so far, had missed but now I had that to worry about too.