From Shagar's perspective he probably was caring, considering his circumstances, I can manage to over look Luso, because I have a bigger thorn in my side.
My biggest pet peeve with this manga is Shagar's relationship with the kingdom. Like they literally set him up to choose between survival and rape, but now they're all acting like all is well in the land of the living.
I hate both tbh. Luso literally let him get critical so Shagar's energy would get more potent. Shagar literally explained in first 2 chapters that having overflowing or not enough energy for a long period of time can cause serious health problems. So him overflowing repeatedly to the point that he passes out in puddles of blood, should at some point have very negative effect on his body.
And then the Kingdom. In the 2nd fucking chapter he detests the Kingdom and people in it because they put a seal on him, yet were mad when he shared his energy with anyone and everyone because he just had too much and he couldn't be picky with who he shares it with. He literally said he is mad at the Kingdom (King) because they are the ones making to exhange energy, yet are still mad the people he shared the energy with, created problems.
And then later chapters as well touch up on his stance
Yet in volume 2 the King is yeah no foul. And Shagar is like "Ofc bestie no biggie" like dude. DUDE???????????? Are we reading the same fucking story
I still dislike Luso, but I just hate the kingdom more. When I read chapter 7.5 I "kind of" understood Shagar's you were nice statement. In a world that just kept on taking from Shagar, Luso at least gave something even though the relationship was basically a farmer and farm situation, with Shagar being the farm.
Also it's been a while since I read this but wasn't in inferred that Shagar could have released himself or something, if that's the case why did he put himself through all this.

SPOILERS!!
Dawg wtf is this hoe shagar talking abt at the end of the second volume going bout sum ‘you were kind and caring’ to luso like this is NOT the same dude???? Are we still talking about that microaggression master rapist motherfucker from the first volume??? Did you forget how you implied he only comes to help you after you’re in critical state???? Hello???? Hello???? Hello????????