Narayana is supreme Parmatma ,independent and jeeva is dependent .Everything is done by the grace of God .Everything is done by HIM and whole world ,our circumstances and consequences are all under HIM , Then why he adjudicates karma phala to us and makes us suffer or enjoy attributing it to US the soul[jeeva]?
The answer to this lies in gayatri " Dhiyo yah na prachodayat" !
God does not get acts from us by force or by making us helpless . He makes a soul act by inspiring his mind [buddhi]. This is known as prachodan . Man faces certain circumstances because of karma , God inspires his mind under these circumstances [through tatva devatas and rakshasas ] Soul owing to his nature and buddhi reacts to the situation through his ichcha ,kriya and gnyana shakti [which are datta swatantra by GOD], Thus his reaction results in karma phala and its subsequent lepa to the soul. This karma phala is attributed to soul because Jeeva out of his own buddhi attributes this to himself as 'I' and 'mine' .
If jeeva attributes it paramatma with 'krishnaarpana' then he will not undergo the karmaphala consequences.