Harry is rescued from Azkaban by.. Himself? A story of Technology, Magic and Terraforming. Not a crossover.
Placing the item in the pocket of the black dress pants he was wearing, Harry placed a pair of glasses with dark lenses over his vivid green eyes. Taking two devices from his belt, he pointed one at the door and pressed a button. A beam of light was emitted from the item and the door was disintegrated, as was the dementor that was just about to open the door.
The other device went over his ear, and a tendril left the item, went down the side of his cheek and attached itself to his throat. With the door open, screams of fighting above streamed into the room.
"Potter to CIC. Arrived at destination. Escape path secured. Fighting has commenced outside. Activating camouflage." A button on his belt was pressed and his clothes transformed into a filthy set of robes, his face appeared dirty, and his glasses became the same as his old ones with cracked lenses. "Confirmed Potter. We receive you on dradis. Good luck and good hunting, Sir."
With a slight roll of his eyes, Harry sat himself down and waited. On the inside of his glasses, numbers went by, allowing him to see that three persons, each reading as just above a squib in power were coming towards him. The one with the most power of three, which wasn't saying much, was reading as an Animagus.
It took them several minutes to reach him, and when they did Harry's suspicions were confirmed. In the middle of the three looking at him, and not at all noticing that the door was gone, was Peter Pettigrew. The two grunts with him, Crabbe and Goyle the elder, moved into the room and took Harry by the arms, lifting him up to his feet.
Seeing the smirk on the face of his parent's betrayer when he entered the room, Harry pulled a tiny item from his pocket, unnoticed by either of the people at the door, so when he was put on his feet, he stumbled forwards into Pettigrew, placing a tracker on him.
There was an almost shriek of shock from Pettigrew at this, but when no attack came, he decided it must have simply been because Harry hadn't used his legs for some time. Seeing a weakened foe, Pettigrew decided it was safe to taunt him, "I never set out to have your parents killed, Harry... But at least now I've won. My lord is going to give me Godric's Hollow when He takes control of the Ministry." He didn't expect anything from the 'weak' Harry, and he got nothing in return... Other than spit in the face.
"Why you!" Pettigrew spluttered and wiped his face. "You're lucky the Dark Lord is waiting! Let's go!" and walked out of the cell, the two oafs behind him dragging Harry.
A/N: Remember, this isn't a cross-over. I just like the word Dradis from Battlestar Gallactica as a term for scan/radar