Don’t mess with Major General Olivier Armstrong or her younger brother Major Alex Armstrong.
From the anime series Fullmetal Alchemist: Brotherhood
Shenyun Li and his younger twin sister, Shenhua, are both arrogant and ruthless but highly skilled fighters who enjoy making their opponents suffer in the arena.
From the anime series Gakusen Toshi Asterisk (The Asterisk War: The Academy City on the Water)
Even though Takeru Kusanagi’s little sister, Kiseki, has dangerous (and sometimes uncontrollable) magical abilities, he will do anything for her sake simply because they’re family.
From the anime series Taimadou Gakuen 35 Shiken Shoutai (AntiMagic Academy 35th Test Platoon)
In a time when androids are used as everything from construction workers to housekeepers, Naoko Sakisaka sees them as mere things, while her younger brother Rikuo’s views change over time.
From the anime series Eve no Jikan (Time of Eve)
When Ai Ninomiya is not busy kicking her younger twin brother, Makoto, for fun, the two enjoy going scuba diving.
From the anime series Amanchu!
Image from the anime series Amanchu!