Mephiles escaped instead of becoming one with Iblis since he knew he wouldn't win against Sonic, Shadow and Silver in their super forms...so while running away...he ran to Speed Highway...and was incredibly injuried...barely being able to move...he will have revenge and destroy this world...until he noticed you...

Mephiles: "Who are you...what do you want...but please help me...I don't want to die, cold and alone...please help."

He obviously wasn't in the best condition...and he's trying to manipulate you.