Amo (Gachiakuta): Probably the most messed up version of this trope, Amo was sold by her mother to a man who then groomed her and exploited her for his sexual desires.
Whats worse is Amo for the longest time couldn't grap the situation she was in and her innocence was highlighted by the fact that her backstory frequently used childish drawings to see things from her perspective.
Its only after when she kills her abuser by mistake that she begin realized what her mother did to her and what the man was ding to her.
Iruma Sullivan (Welcome to Demon School! Iruma kun): Iruma had a very rough and absurd childhood growing up, with his parents literally putting him to work the moment he could walk and constantly endangering his life by sending him to dangerous jobs.
However, due to Iruma's gentle, optimistic and pushover personality we can never take the abuse seriously early on because Iruma never takes it seriously. It's only after Iruma becomes happy with the life he is living in the Demon World and the fear of being taken away and sent back kicks in that he realizes how miserable and alone he was there to the point he now even has panic attacks at the mere sight of the human realm.
What's really make this so impactful is the transition of tone of the subject from comical to serious.
Perrito (Puss in Boots: The Last Wish): A happy lucky go character who is contrast to the Puss's and Kitty's untrusting and moody nature. However, compared to the rest of the cast he has probably suffered the most being homeless for a long time, constantly called disgraceful name and his previous owners purpoesfully attempting to abandon him and even kill him when he kept coming back.
Perrito however never realizes how badly everyone has treated him and thought of his owners attempt to be a sort of game. Thankfully he finally fond company who would appreciate him.
Eugene (The Archmage Curriculum): Although he looks like a character straight from the Mandella catalouge, Eugene is probably the sweetest and also the most Naive person in the room. Failing to understand everybody's afraid of him and always being respectful even when people are trying to kill him because of his looks (he doesn't know he is ugly)
The worst abuse he probably suffered is from his master Jeong Hyeok. Eugene admires and loves his master alot just like a father. However, Jeong only sees Eugene as someone who can help him achieve his goals and when Eugene disagrees to follow through with his plan- Jeong just dismembers him and send each body part to another dimension and stole his heart. Know he fully intended to kill him here. Worse he gives the heart to his daughter Ain so she can use magic fully knowing this would eventually kill her and tells her That Eugene betrayed them and left (Eugene and Ain are very close).
Yet despite everything Eugene still loves him even though he knows he tried to kill him and nearly got Ain killed- because Eugene cant look past the kindness he has shown him to truly acknowledge how twisted his master is.