the whole scene bring me memories of dark souls 1 sewer with those slimes failing into you....
Well could be she just forcing his movement and no taking "control" at all, even more when she its suffocating MC.
So, Chronic Over-Analyzer here, usually keep to myself but I really dig this girl for some reason so brace for the rant. As for what exactly is happening, I'm going to split my theories/wishful thinkings into gameplay and lore perspectives.
As for lore, she seems like a cross between a slime and a living suit. Judging by the fact that the MC's arms end up through arm holes that don't appear to be on the grounded one, I'm guessing she is just gooey enough to flow over his arms before becoming solid again. Which explains some of the MC's difficulty pulling her off him before it's too late. I like the sneaky, deceptively dangerous aspect to her. Slow and seemingly harmless on the ground...to distract you from the one coming from above. Also she seems so pleasant about the whole occurrence, even while MC is trying desperately to pry her off she's got this amused "Aw that tickles~" expression on her face, right before she completely subdues him. Now for what she is really doing to him, I'm hoping the sound effect used will help narrow it down but I have two main guess based on his body language before, during and after.
1) Electrifying him into submission: Judging by the energy lines around her and the way his limbs stiffen, it's possible that she is giving him some kind of shock. Nothing lethal or likely even painful, just enough to take the fight out of him, hence his arms drooping afterwards. She could then use those same currents, more finely tuned, to manipulate his body into what she wants to do. In this case, give her fellow bunny slime a snack.
2) Complete Assimilation: She is essentially fusing them together on a deeper, possibly more permanent level. How exactly this is done precisely(his body/mind merging with hers, tentacles from inside her flowing into and throughout him, etc) who knows. At this point, MC is likely still conscious inside of her, but she's overridden control of his body. If he's lucky, he can still maybe view the outside through her eyes like a mask.
It should also be noted that the second bunny slime that was approaching him that entire time, stops the moment the ambushing does what she does to overpower him. Which seems to tell me that she recognizes that his resistance after that point is no longer an issue.
And as for gameplay...I kind of want her to be an "instakill" sort of monster, but at least semi-fair. So when she lands on you, if you can pry her off quick enough you'll be ok. If you take too long, or she lands on you at low enough health, she overpowers him and makes herself a permanent fixture on his body. At which point she has fun with it herself, or goes to find a second monstergirl to enjoy him with.
Alternatively, I'd like her to be an instakill only when paired up with a second bunny slime(or similar type monstergirl). So, a single bunny slime only has enough mass to envelop half his body, but if a second bunny slime gets too close at any point after the first has latched on, the second one will similarly envelop the other half of his body, before fusing with the first one in the middle and completely sealing him inside them. Which of course would be a gameover since, while he is certainly still alive, he no longer has any realistic means of pulling them off him or resisting what they do to him while inside.
Then you'd have those stressful moments of being full health, but a bunny slime gets lucky and manages to latch onto your feet up to your waist(probably with her head placed at MC's grown like a belt buckle, so that that part of his body is entering her mouth from behind her head, and she's happily sucking on it in there like a piece of candy). This would just be an annoyance usually...until you see the ominous shadow of a bunny slime on the ceiling getting closer and closer to being right above MC's head... So while they are kind of slow and kind of predictable, any room with multiple of them close together would be a death sentence(well, more like life imprisonment with indefinite conjugal visits) for the slow and unobservant.
Ok, rant over for now. Man I need to stop thinking so hard about half-minute pixel art...
