i think i have a solid idea of how the "ackerbond" might work.
Ackermans were created to be the sword and shield for the eldian king, right? but they can't be controlled the same way Eldians can. so an Ackerman isn't a 'slave' to their bond with another person, but i feel they love more intensely than a regular person.
being a product of Titan science guarantees infallible strength and power of a Titan. but they're also human, so it makes sense that they'd look for connection to another person in the same way any other person would, but specifically an equal. so Ackermans look for something in a person that they themselves lack.
Levi looked for a bright future and a peaceful world, even for someone who has suffered and seen suffering as much as him, in Erwin.
Kenny looked for compassion, even for garbage like him, in Uri.
Mikasa looked for true love, even for a world as cruel as hers, in Eren.
*disclaimer, i don't think the "ackerbond" must be romantic.