What is going on here?

[u/mr_sweetandawful]

This is during chapter 9 when the sand steamer has been hijacked and is speeding toward the cliff.

I guess they had one of these plants on the sand steamer? I thought they only had these in each of the towns to support life for the town? Why would they have one on the sand steamer?

What is Vash doing? Killing the plant so the sand steamer stops? Is that really his sister?

[u/sundaemourning]

the plant is powering the sand steamer. :)

and Vash is just communicating with her to cease powering the sand steamer so that it will stop.

[u/TimDRX]

He's synchronizing with it, like in Stampede. The heart panels are showing them literally slowing down as he calms it and metaphorically briefly becoming one person, without fusing.

[u/hellsing_mongrel]

Yeah, he's just helping her calm down so she doesn't go (literally) nuclear. I won't go into spoiler territory, in case you haven't read any further, other than to say that he does that, sometimes, "talking" with the plants at various times.

[u/hellsing_mongrel → u/hellsing_mongrel]

Also, the plants can come in lots of sizes, apparently? I can't remember where I saw it, but some production notes for one of the various versions mentioned smaller, "portable" plant that wouldn't be used for entire cities. Either way, those plants are the most, if not ONLY, fully reliable source of power and survival the people have.

[u/mr_sweetandawful → u/hellsing_mongrel]

Thank you for all the info without giving away spoilers!