This is really good. The only thing I think would be needed would be for your partners to be attacked more often than just once or twice a stage. Having them also being able to be attacked during boss fights would also further spice things up a bit. It would also be pretty great if those moments could escalate (possibly by taking too long) or have some variance to them or something. It's just such an interesting way to mesh the H with the gameplay you've got there, and the potential it has is really nice.
Viewing post in Starbreed [3D Rail Shooter] comments
It's possible things may get shaken up a bit in later levels. I did want to keep the initial levels fairly straight forward to ease learning curves. I'm not sure if I will be expanding on the "help" sequences specifically , but I do like the idea.
I suppose one of my biggest reservations on them escalating is that it gives incentive to the player to let your ally die/lose. While I don't think "lose" mechanics are inherently bad in H-games, I feel like it doesn't work in favour of Starbreed's structure. This is just how I feel about it, though. That being said, that doesn't necessarily mean the "help" mechanic can't be expanded on.
I would think the tradeoff would be your passive and active abilities from that ally would be disabled for a time (really, their active should be disabled while they're grabbed in the first place when I think about it). That said, I do understand not having them escalate. The earlier points I brought about them simply being attacked more often should be good (maybe an option adjusts how often they can be attacked? I dunno). Especially if it can happen during boss fights, since that would make them more dynamic. Hell, you could go a step further and add special boss help sequences, though I understand that'd mean adding more animations and such for something like that. But yeah how the game does the help mechanic is cool, so I wanted to bring it up.