Board Thread:Questions and Answers/@comment-187.104.5.143-20180214155359/@comment-71.38.23.146-20200319003008

I think it is because Liz was the first reincarnation that he's lived with for a while, and has grown a very strong relationship with that once Fraudrin killed her, Meliodas got fueled with rage because of all of the memories and deaths he's witnessed of her dying. But also seeing her die in front of him made him think that he could've stopped it, and thats why he got so mad.