The tried a hook-up with Renault a couple of months ago but that got shot down by Nissan and the French Govt, so the next company in the Rolodex was Peugeot.
When they were trying for Renault, the smart money was saying that was a great play because Renault (whooda thunk it?!!?) was ahead of almost every other Euro automaker (and well ahead of FCA) in electric vehicle tech, as in a big slate of electric cars mere months away from showrooms, vs 3-5 years for FCA. FCA muckity mucks thought that a hook up with Renault would have made all of Renault's elec-tech available for use in FCA product much sooner than the home-grown.
Not sure what the attraction of Peugeot is, other than your typical mega-merger buzz words like "synergy" and "complementary product" which always looks good on paper but rarely accrues to the bottom line. That and the fact that the girls get prettier near closing time.