Fictional System Documentation

Fullmetal Alchemist Brotherhood

Ling Yao, 12th in line to the throne of Xing, enters the story in search for a Philosopher's Stone. Said to be the secret to immortality, Ling seeks to claim the stone amidst a heated competition for the throne to gain the favor of his father. His search eventually results in the Homunculus Greed assimilating himself into Ling's body. To Greed's surprise, Ling willingly accepts this assimilation and maintains his sense of self as a result.

Although Greed has the edge in combat when it comes to brute force, Ling proves himself to be a useful asset by way of his agility and keen senses in dark environments. By switching depending on the situation, the two are able to handle fights that neither of them could have handled alone. It is difficult to go into further detail without massive spoilers, so we encourage you to analyze the dynamic further during your own watch/rewatch/reflection.

The Owl House

One of the 3 main characters of The Owl House, Eda is a powerful witch who becomes cursed with the Owl Beast, who lashes out and takes control at seemingly indeterminate times. Eda is able to keep the Owl Beast down with her elixirs, but it is proven to not be a long-term solution. The time comes when she must confront the beast and accept it as a part of herself.

The relationship between Eda and her Curse is often interpreted as an analogy for dealing with various mental illnesses. While this is a valid interpretation, it can more literally be seen as a headmate of Eda's system. In S2E4, Eda demonstrates a brilliant example of being aware but not in front as she hears her mom call out to her, powerless to talk back. She follows up with the wonderful switching quote of "my turn to drive!"

S2E8 is when Eda finally makes peace with her owl companion, unlocking a new form for them to use together. In Future episodes such as S2E9, she talks with the Owl Beast in an obviously plural way. If only all systems could get a cool new form by bonding...

Celeste

Madeline's journey up Celeste Mountain requires her to face a Part of Her she wishes she could leave behind. The Mountain, said to be a mountain of healing, "can't bring out anything that isnt already inside you". This Part of Madeline continues to keep her from climbing further until she finally succeeds and drags them both down even further than they started. The persecution finally ends when Madeline accepts this Part of Her as intrinsic to who she is, allowing them to finally climb the mountain together.

The persecutor headmate is a tired trope of plurality in media (not helped by her canon name being "Badeline"), but Celeste handles this dynamic surprisingly well. Generally, the whole point of a persecutor is to protect the system from harm and is willing to cause harm of a lesser degree to accomplish this. Chapter 6 is an incredible interpretation of what it takes to confront and understand a persecutor, and it portrays hope in reconciliation and understanding. A system works best when they work together.