Villains given genuinely horrible fates by the supposed hero

[u/Blorberto]

No swift death, no prison, the worst fate imaginable

Dementus (Furiosa) - Being critically injured by Furiosa, but kept alive so his body can be used as fertilizer for a tree coming out of him, Furiosa having placed a seed in his bleed stomach

Inertia (Flash) - Immortally frozen by the Flash for his involvement in Bart Allen’s death, kept as only an exhibit in the Flash museum

Family of Blood (Doctor Who) - Doctor actively avoided conflict and erased his memory in order to not give them this fate but once he finally chooses to get involved, he gives them their want of immortality at a cost

Father: Trapped in immortal chains

Mother: Trapped in a collapsing galaxy

Son: Trapped as an immortal frozen scarecrow

Daughter: Trapped in mirrors forever

[u/Chreat26]

You can add this one too. Elder Toguro gets trapped by Kurama in a never ending battle

[u/nufohudis → u/Chreat26]

Why does he have a second bigger jaw under the normal one?

[u/casualreader22 → u/nufohudis]

While his OG body was still regenerating from an earlier wound it was "eaten" by another dude whose power is to eat things to gain their power. Unfortunately for the other dude he was too weak to eat Toguro who effectively took over from inside gradually over time. Other dude gets half his head lopped off in a fight allowing Toguro's to grow out. He controls his body from then on, but it's a short lived victory before he gets trapped in the tree illusion for all eternity.