>>57889510
In Madoka Magica, the girls are manipulated by Kyubey into trading their souls for power. The girls are motivated by stuff like wanting to protect people they care about, and they think being magical girls will help them do that. On Kyubey's side his secret motivation is protecting the universe from entropy, and with a goal so big he has no reason to give a shit if a bunch of naive magical girls suffer and die horribly in the process.

So swap Kyubey for Giratina, the magical girls with Mays, and their motives with ones unique to each of their individual personalities.