Note-this is all purely speculating on the new character Silver THE "Ice Demon Slayer" Typo in the title 353 and beyond
Lets get down to business
So in the latest chapter we're introduced to an "ice devil slayer" named Silver who ironically seems to be a silver fox type person., and in the 2nd last page  he said he was visiting a grave, perhaps that of a lost loved one?
So what i'm speculating is that Silver who uses Ice Magic, is in actual fact is visiting Gray's grave and could very well be his son. As When Deliora attacked Gray's town perhaps his parent(s) did not die and survived; Silver now out for revenge consumes "the souls of demons" who had taken away the life of his son Gray.
So that was my thoughts on the new character Silver from the dark guild Tartarus