Caution: spoilers ahead for Attack on Titan's "Two Brothers"
Attack on Titan season 4's "Two Brothers" episode contains the shocking and gruesome moment Porco lets Falco eat him - why make such a sacrifice? Since accidentally ingesting Zeke's spinal fluid earlier in season 4, the writing has been very much on the wall for Attack on Titan's young Falco Grice. As part of his grand euthanization plan, Zeke immobilized the Paradis Island military by spiking their wine. The Beast Titan now only has to cry out, and anyone who drank the stuff suddenly transforms into a Pure Titan. Though intended for enemies only, Falco inadvertently ended up in the same unfortunate predicament.
The inevitable happens in Attack on Titan season 4's "Two Brothers," and Zeke's call sparks a mass invasion of flailing fleshy giants in Shiganshina, including the likes of Dot Pyxis, Nile Dawk and, indeed, Falco Grice (no Saul Goodman this time, sadly). Falco is a mindless, lumbering Titan, and begins chewing on Reiner's nape. The Armored Titan resolves to let Falco eat, which would mean Reiner dying, and the youngster returning as a Titan-shifter. Before he can, however, a battered and bloody Porco Galliard steps in and encourages the Titanized Falco to dine on him instead. Porco is gobbled up, and Falco will inherit the Jaw Titan.
Reiner had two obvious reasons for letting Falco eat him. The owner of the Armored Titan has been experiencing an identity crisis ever since that fateful first visit to Paradis Island, and can't comprehend his worth beyond the battlefield. Also, he and Falco shared a close bond through their mutual desire to protect Gabi. But why does Porco offer himself up when Reiner was happy to oblige? The main reason is Porco realizing he's a dead man walking. Since the Shiganshina battle began, Porco has endured heavy hits from the Super Jaeger Bros., Eren and Zeke, culminating in the Jaw Titan getting his head pummeled by the Attack's hardened fist. When Porco emerges, he apparently lacks the energy to trigger his Titan's healing powers, and senses death approaching.
Considering Porco is both standing and talking at this point, whether the Jaw actually would've died from his injuries is a matter of debate. We've certainly seen Attack on Titan characters recover from much worse. Irrespective of Porco's condition, there's a deeper reason behind the sacrifice he makes, which is not just for Falco's sake - but for Reiner's also. When the Armored Titan makes contact with the Jaw's mangled head, Reiner is mid-grapple with Eren Jaeger. Eren's Founding Titan power allows Porco to view a memory from Reiner's past, which just so happens to be the moment Marcel, Porco's brother, shockingly admitted to manipulating Marley's Warrior Candidates system so Reiner would take Porco's place as the Armored Titan. This revelation from the past proves Reiner never should've become the Armored Titan, nor fought on Paradis Island, nor currently be in a position to offer his life in exchange for Falco's. Reiner only finds himself here because Marcel was preventing his younger brother going to war.
So there's a twinge of guilt in Porco's voice when he says, "There's no denying it now... I was always better than you." Porco can't bring himself to let Reiner die, when Porco is the real reason Reiner's here in the first place. Falco eating the Jaw Titan adds another layer to Attack on Titan's "Two Brothers" episode title. The phrase isn't just referring to Zeke and Eren (or, indeed, Falco and Colt), but also Porco and Marcel. The older brother using Reiner to protect Porco in the past leads directly toward Porco letting Falco eat him in the present.
Attack on Titan season 4 streams Sundays on Funimation, Crunchyroll, and Hulu.