ᴄʜᴀᴘᴛᴇʀ 𝟷: sᴛᴜᴍʙʟɪɴɢ ᴀᴘᴏɴ ʜɪᴍ

Rin okumura, was born and raised as the spawn of satan, at this time rin is also 17, but because to him being half demon, he ages much slower compared to a human, due to this, we have tiny rin! Only looking around the age of 4-5! What would happen if the Grigori were to find out about this when trying to find satans weak point?