Donnie, now working for the Brotherhood, still misses his love interest Lin from his days in the Westside Rollerz and mourns her death. He even has a Voxel, Lin's preferred type of car with "in memorial" written on it. It makes you feel somewhat guilty when the Boss kidnaps him straight after.
Carlos is unable to supply the Boss with much information about the Brotherhood. Though disappointed in him, the Boss reassures him. Sadly, this makes his death in the next mission all the more heartbreaking.
The Boss visits Gat in the hospital after he got impaled with a katana and shows genuine anger throughout the Ronin missions after what happened. Given the character it's quite touching.
Gat: "So, the bastard's dead?"
Boss: "I cut him up myself. How are you feeling?"
Gat: "She's dead. You really gotta ask? Funeral?"
Boss: "We're waiting for you. How are you holding up?"
Gat: "Doc says I'll be up to murdering in a couple of days." Boss chuckles at this. "Well, he didn't say murderin', but you get the idea."
Despite how much Gat and Aisha quarrel with each other, the amount of emotion Gat displays during Aisha's funeral shows how noble he can be at heart. He brutally pummels Shogo Akuji for interrupting the funeral and has nothing but Aisha in mind.
This soft side is also displayed when Ultor attacks the Saints. Gat informs the Boss to check Pierce and Shaundi and make sure they are okay.
In the penultimate mission of the Brotherhood arc, one of the Saints soldiers can be heard shouting "THIS ONE'S FOR CARLOS!".