Warning! Spoilers ahead for Sinister War #1
In the latest Spider-Man event Sinister War, it's revealed why the demon lord Mephisto needed someone like Agent Phil Coulson to do his bidding and create the twisted reality of Heroes Reborn. While Doctor Strange is seen in this issue confronting Mephisto about Peter Parker's soul, the demon lord reveals a key piece of information about his own nature, which informs how things transpired in recent comics featuring Coulson as his minion. Not only that, but it also implies how the newly formed Council of Red (an assembly of multiversal Mephistos) will operate in the near future against the Avengers.
In Heroes Reborn from Jason Aaron and Ed McGuinness, reality was warped and history was twisted so that the Avengers never assembled, instead they were replaced by Coulson's puppet heroes known as the Squadron Supreme of America (analogs for DC's Justice League). Furthermore, Phil Coulson installed himself as President of the United States and his master Mephisto as the country's primary god to be worshipped. The final issues of Heroes Reborn revealed that Coulson rewrote reality using a Pandemonium Cube, also known as a Helladron, which is a dark version of a Cosmic Cube given to Coulson by Mephisto himself. However, why didn't the demon lord just use his own cube in the first place rather than running everything through Coulson as a stooge?
Interestingly enough, Sinister War #1 from Nick Spencer and Mark Bagley provides the answer when Doctor Strange demands to known what Mephisto took from Spider-Man and his soul. However, Mephisto counters by reminding the Sorcerer Supreme that that's not how he operates. By his own nature, Mephisto is unable to take anything from anyone. Anything he gets must be given, leading to his use of trickery and manipulations such as the cutting of deals. For Spider-Man it was the erasure of his marriage to save his Aunt May. For Phil Coulson, it was to be resurrected in exchange for complete servitude to Mephisto.
So it makes sense why Mephisto would work through Coulson as he wouldn't have been able to directly use his cube and rewrite reality himself. He always needs to trick his victims or use one of his "maggots" (what he calls his minions) to carry out his will. This also informs the potential future actions of the teased Council of Red, a collection of Mephistos from across the multiverse who have come together for some dark and unified purpose. However, will they all still need maggots and servants to work for them, or will the rules change due to their collective power and darkness?
Whatever happens, it's nice to know that Mephisto has his limitations, though he's certainly cunning enough to often get what he wants from people all the same. That's what makes it a sick and twisted game for the lord of Hell. Here's hoping that Spider-Man will be able to restore his soul with Doctor Strange's help and that Marvel's collection of heroes will be prepared to face the multiverse's collection of Mephistos in the near future.