After the Zilla Wars conclude, Roger remarks with regret as to how many were killed or wounded. Shiro reminds him of scenes that were worst before the rangers came to the Groove.
In fact, being a member of the Defense Force is essentially a thankless job. They're the first line of defense against the Monster of the Week and at least dozens of members will die before the Rangers are victorious. It makes you wonder why so many people volunteer to join the Force with such a bleak job description.
The abuse leveled at Euphemia in chapter 26.
According to what Hitomi sees in Chapter 28 during a Tarot Reading, abuse is not the right word to describe everything.
Monsha's account of a horrific encounter during the bar scene in 28. The scar that he got was minor, but the story still haunts him, especially as he'd lost a good friend and nearly lost his own life.
Even the very thought of Lordgenome being Nia's father still freezes her emotionally.
The life and tragic death of Akira Amada as told in Parallel Works 13.
Kaworu himself is shown to be troubled and tearful when reflecting on Akira's memories. As if this young man's story served as a mirror for Kaworu's own created role as SEELE's puppet and where it would lead.
The high implication that Kamina is slowly dying from his wounds given by Thymilph (which killed him in Gurren Lagann's Canon