The rewards from Haley, Claire, and Gloria were good, no, wonderful, but it was not something useful for him now. But the one he got after Sonia was just right.
He got the map to function like Jack Sparrow's compass from Pirates of the Caribbean. Using it, now Sonia and Daru stand outside the building where he knows William is. He can see it through the map.
He knew the structure of the place from Gil, so he knew the lab was underground and well-isolated. He saw five dots down, which could be William, Salvo, and four of his men. Then there were about twenty in the other part of the building.
With the powers he holds, he didn't see the need to delay it any longer or the need for any plan other than to walk in and kill every single man inside. That's just what he did. He handed Sonia two guns, he carried two.
Then, trusting Sonia to hold her own now with a firearm, he just walked in. Shot the two guards, he let the other run inside. The guy, in panic, still tried hitting him, as he pointed his gun behind him to shoot. But not two steps forward, he fell with a hole in his head.
Daru walked in, ignoring the falling prey of Sonia's. Past the guy, he picked the submachine gun. He had his eyes on the map always so he knew where everybody was, knew what would be the best blind spot. He saw a guy running down to inform Salvo in the lab. 'Doesn't matter.' He thought in cold judgment. And it didn't, as he shot down men like they were sitting ducks. Sonia, too, raked in heads like a reaper.
Daru walked up to the door down to the lab, shot through the door aiming right at the heads of two guys. The map and the combat skill were just too much of a cheat. The men didn't stand a chance. Salvo was terrified but also seething, "Do you think you can get aw…"
No fucks were given but a single bullet was, through his skull. Now it was William, Sonia, and Daru.
William already looked roughed up, must be by Salvo. "Daru, please…"
He begged, but it was not gonna work. Sonia walked in front of Daru. Daru didn't stop. No matter how much he wanted to kill him, he knew that after what William had done, his death was destined to be at the hands of Sonia. And it was not a swift one. Sonia spent her whole heart in torturing him. Once William was not even able to voice a plea, Sonia killed him just like he killed their mother.
This was, though, not the last of the violence as what Salvo said about Tuco not letting it go was true. After killing his major money bank, William, and his loyal dog, Salvo, Tuco would be out for blood. But this time he has an easy way out.
Going to the detective that has been on William's ass and trying to do a bust on the Pink Rock, Daru made a deal. He would give him the last stash of the drug and help in purging out the whole of Tuco's operation, all he has to do is sneak him into the prison Tuco is in. After that, Daru assassinated Tuco and got out, all in a week.