Venice (silver's prototype) and Silver are hedgehog brothers on the run from Mephiles and his goons. He either wants them dead/captured because they posses immense psychic powers that can pose a threat to Iblis and by extension, him. Venice and Silver run around the ruined world in search of a sanctuary where Mephiles won't be able to find them. (also its not obvious in the image but Venice actually has a laser gun or smth in case he can't use his psychokinesis)
Mephiles' "goons" are the prototype Infinite designs. They were created using shards of the phantom ruby. Infinite himself used to be under its control, but broke free. The remnants of the ruby's power took the form of the a smaller version of Infinite's ruby self. He joins Venice and Silver at some point because he wants to get away from Mephiles and the ruby squad too.
Blaze and her prototype are in this too, but i haven't decided exactly what is her role in the story.