Early in the season Wells notices the changes in the paper, especially the ep where Barry lost his powers. The critical change was the 'Crisis' headline. Wells took steps then to make sure Barry was repowered so that the crisis would be averted.
Wells has come to realize in the last 15 years that Barry has to live, and has to have his powers, or else there is no future to go back to. Wells didn't know this 15 years earlier when he arrived to kill young Barry.
Wells need the giant particle accelerator to be built and to malfunction, or else why build it, and why, according to his ex-protégé (sorry forgot his name) start it up knowing it would blow. This event was critical to creating The Flash.
15 years ago Barry must have injured Wells, damaged his speed suit, drained his power, or otherwise reduced his speed enough to prevent him returning to his future.
Wells must have known that a particle accelerator was built and malfunctioned, creating The Flash. I think it likely that the real Wells, whom he killed and used for an identity, had/would build the accelerator. Wells took his identity so that he would control the process and probably hoping that he could repower himself through the process that created Barry's Flash.
Basically, 15 years ago Wells didn't realize Barry had to become the Flash, so he felt free to go back and kill him as a child. In the intervening years he learns what a mistake that was, and realizes he needs Barry to both ensure the future and to repower himself.
Wells has come to realize in the last 15 years that Barry has to live, and has to have his powers, or else there is no future to go back to. Wells didn't know this 15 years earlier when he arrived to kill young Barry.
Wells need the giant particle accelerator to be built and to malfunction, or else why build it, and why, according to his ex-protégé (sorry forgot his name) start it up knowing it would blow. This event was critical to creating The Flash.
15 years ago Barry must have injured Wells, damaged his speed suit, drained his power, or otherwise reduced his speed enough to prevent him returning to his future.
Wells must have known that a particle accelerator was built and malfunctioned, creating The Flash. I think it likely that the real Wells, whom he killed and used for an identity, had/would build the accelerator. Wells took his identity so that he would control the process and probably hoping that he could repower himself through the process that created Barry's Flash.
Basically, 15 years ago Wells didn't realize Barry had to become the Flash, so he felt free to go back and kill him as a child. In the intervening years he learns what a mistake that was, and realizes he needs Barry to both ensure the future and to repower himself.