Recently the memory of this one shoujo manga has popped into my head and I went to see if it was ever finished. It's about a troop of orphan acrobats that act like a family. The girl gets adopted into the "family" and likes one of the guys. At the same time she's wanted for inheriting some power or something. I can't remember the name and would love to find it again.
It's a seinen but it seems to match a bit http://www.mangago.zone/read-manga/yakushoku_distpiari_gesellschaft_blume/
Doesn't being a sharing still take their energy and what about the lifespan differences? Feels like they just wanted to end it.