The Maxwell's Demon is a scientific concept created by James Maxwell as denial to the idea that it's impossible to produce infinite energy. The Servant version takes the shape of concept but is actually a personification of humanity's desire for infinite energy. A nigh-useless Servant whose only power is to make batteries never run out. His purpose is to allow someone to harness infinite energy to make humanity happy, and his wish for the Grail is to prove the theory he's composed of, so that his infinite energy can be assessed by anyone.
But he always fails his purpose because he only gets summoned by bad Masters that he feels forced to sabotage. In Koha-Ace's original Redline, he's summoned by Hitler's body who wants to use his NP on the Grail and use the infinite Grail to summon the real Hitler as an artificial god, but he knows that the Nazis won't make humanity happy, so he intentionally keeps quiet about the glaring flaws of his Master's plan and then manipulates the completed Neo Fuhrer for his own personal goals. And in Gudaguda 4, he's summoned by a cultist using children in jars as infinite mana batteries, but he knows child-exploiting cultist won't make humanity happy, so he pulls the strings to make every character in the story oppose his Master and then kills himself when he's most needed.