They both seem to be smart for their age, the older twin acts more responsible, while the younger twin is a bit more naive. I think they will grow up to be quite capable super meat buns.
The MC, in my opinion, is a bit different from the usual 'strong people in their past life and died on a mission'. He, instead, died from helping other people escape. Even though he's said to be vicious and stuff, he died from a moment of softheartedness for a man who liked him and wanted him to follow them. I like it how in the summary, his introductory paragraph said he's all hard-faced and scary, but after that, he's bargaining for food with his two buns while planning to turn them into rich 2nd generation young masters.
I don't know much about the original owner of the body, but from what the buns were saying, he seems re****ed or mentally lacking.