What are your thoughts on the idea of the concept where the MC who found himself in possession or in partnership with robofu, and this robot slowly gains confidence to the point of asking for more and more upgrades but the MC doesn't feel the need to always upgrade.
Then one day like all GF's eventually do,she starts hinting toward something on the lines of marriage, but it's a neuro implants or even augments such as cyborg.
Perhaps the MC has a heart defect, and the robofu after succeeding in getting him to replace his heart with an artificial one gains an addiction to "improving" his body with artificial parts. Perhaps the story could lead to the Robofu hitting some sort of plateau, and now starts dabbing in illegal parts.
A lot of people these days have more enjoyment in perfecting games through mods than they do through actually playing the game.