Raleigh lies when he says that the last he has of his brother is the fear and falling as he was ripped out of Gipsy Danger. No, Yancy is a ghost in his mind.
Explaining the lingering Drift between their minds isn't something he could have done, even before. He's a Ranger, not a poet-and that's something they all agree on. To handle not just the neural handshake but also its clinging tendrils...Raleigh thinks that it's little wonder that most Yaeger pilots are close relatives and secondarily friends and partners.
When they turn their back in Alaska, their minds are fitted together, spread between their two bodies and Gipsy and lacing them all together. When the kaiju tears at Gipsy's arm, the pain echos through Raleigh more acutely, less focused on the part that is Yancy. When the helm is breached and Yancy is stolen, their minds are still entangled.
Bad enough, they'd joked, that the other's mind would be crowding into their head when they walked as distinct, separate minds. Part of each was torn away when the neural link is broken without the handshake's end.
It's hard to say whether Raleigh would have gone on without Yancy ghosting along the edge of everything. They've both always been stubborn sons of bitches-Yancy cuffs a glancing blow against Raleigh's head for saying that about Mom and it hurts because he can't fucking feel the hit-because they're brothers who grew by nurturing the fight in the other.
Raleigh can't deal with the broken edges of his mind-he disappears before they can ask him about compatibility with another pilot-and without a plan or an acheless-body stumbles away.
Yancy stands at the edge of painfully-empty space where his thoughts used to drift. He is a shadowy silhouette that keeps Raleigh from stepping off the top of the Wall.
Years pass.
Pentecost is desperate enough that he will take a sharp-edged mind like shattered glass-the helm tears open screaming steel and breaking window and the claw and Yancy and Yancy turning and Yancy falling and-and think to fit it against a soft new mind.
Whatever Raleigh was expecting was not the monster in Mako's mind.
Red shoe walking crying lost alone fear running hiding tall.
She carries Tokyo with her and all the years since; they shoulder that and the combined weight of Raleigh and Yancy's memories. He owes it to Mako to tell her at least part of the weight they shoulder in Gipsy.
Yancy stands in the corner of the helm while Raleigh and Mako Drift together to seal the breach in their world. He is the heaviest ghost they carry, but it has made them stronger as well.