These from Etymonline
late 14c., possessen, “to hold, occupy, inhabit” (without regard to ownership), a back formation from possession and in part from Old French possesser “to have and hold, take, be in possession of” (mid-13c.), from Latin possessus, past participle of possidere “to have and hold, hold in one’s control, be master of, own,” probably a compound of potis “having power, powerful, able” (from PIE root *poti- “powerful; lord”) + sedere, from PIE root *sed- (1) “to sit.”
According to Buck, Latin possidere was a legal term first used in connection with real estate. The meaning “to hold as property” in English is recorded from c. 1500. That of “to seize, take possession of” is from 1520s; the demonic sense of “have complete power or mastery over, control” is recorded from 1530s (implied in possessed); the weakened sense of “fascinate, enthrall, affect or influence intensely” is by 1590s. Related: Possessed; possessing. The other usual Latin verb for “to possess,” tenere, originally was “to hold,” then “occupy, possess” (see tenet).
mid-14c., possessioun, “act or fact of holding, occupying, or owning; a taking possession, occupation,” also “thing possessed, that which is possessed, material or landed property” (in plural, goods, lands, or rights owned), from Old French possession “fact of having and holding; what is possessed;” also “demonic possession,” and directly from Latin possessionem (nominative possessio) “a seizing, possession,” noun of action from past-participle stem of possidere “to possess” (see possess).
The legal property sense is earliest; the demonic sense in English, “state of being under the control of evil spirits or of madness,” first is recorded 1580s. Phrase possession is nine (or eleven) points of the law is out of a supposed 10 (or 12). With eleven from 1640s; with nine from 1690s.
St. Jerome in his ‘Life of St. Hilarion’ has given us a graphic account of the courage with which that saint confronted, and the success with which he relieved, a possessed camel. [Lecky, “History of European Morals”]
“controlled by an indwelling demon or evil spirit,” 1530s, past-participle adjective from possess (v.). An Old English and Middle English phrase for it was devel seoc.
Are you possessed by your possessions?