- “Yeah...Wait, what?”
- — Sister
Private Kaikaina "Sister" Grif is a Blue Team Simulation Trooper, initially assigned to Outpost 1-A at Blood Gulch; she is also Dexter Grif's sibling. She has been seen naked by Doc, Simmons, Sarge, Grif, and Donut. She was also presumed to have been killed by Lopez sometime between Reconstruction and Recreation, before Season 13 revealed her to be alive. After appearing in Season 15, she was again promoted to main character in Red vs. Blue: The Shisno Paradox. While Tucker sometimes taunts Grif that he had sex with her, Season 16 reveals he and Sister actually abandoned the attempted coitus due to an interruption.
- She is colorblind, which may have been why she went Blue and not Red.
- For a time the Grifball carrier's armor color turned her yellow and not the usual Dexter's orange (it would still be s Grif, though).
- She was the only member of the Blood Gulch Blue Team not to be reassigned in the intermission between Seasons 5 and 6.
- Sister only appeared in a deleted scene for Season 9 and brief shots in Seasons 13 and 14. Season 15 was the first since Season 10 to actually feature the character in more than one episode.
- "Kaikaina" is Hawaiian for "younger sibling", making "Sister" her actual name (though the word is mostly used for "brother"). First revealed in the Season 5 DVD menu, it appeared on the show in Season 14, and actually spoken out loud in Season 15.
- Sister was originally intended to be a sweet and naive homegirl, but when in an audition RT discovered Rebecca Frasier had no problems in saying dirty lines, the character was rewritten as a loud and dumb slut.