Thread:YAREYARE42/@comment-26435553-20160721080231

I did a bit of research because I'm used to seeing に as the subject of the passive sentence too (therefore I was inclined to agree with you), but my dictionary plays a slightly different tune than what I imagined:

子供に甘い　be indulgent to (one's) children 子供に甘える to spoil (one's) children 甘え dependence 甘えっこ spoilt child

犬などが人にじゃれつく (synonym) dogs are playful towards people 子供が親に甘える children nestle up to their parents

お言葉に甘えさせていただきます　(I) will defer/depend to your words

It seems like the subject が/は babies/depends on/spoils the object に.

It's been a while since I dug around in the dictionary. It was a good exercise, thank you for providing me with the opportunity. 