Thematic Bible: The last enemy that shall be destroyed

Therefore, since the children share in flesh and blood, He Himself likewise also partook of the same, that through death He might render powerless him who had the power of death, that is, the devil, and might free those who through fear of death were subject to slavery all their lives.

For He must reign until He has put all His enemies under His feet. The last enemy that will be abolished is death. For HE HAS PUT ALL THINGS IN SUBJECTION UNDER HIS FEET But when He says, "All things are put in subjection," it is evident that He is excepted who put all things in subjection to Him. read more.
When all things are subjected to Him, then the Son Himself also will be subjected to the One who subjected all things to Him, so that God may be all in all.