Your perspective on reality has been forever changed, perhaps due to crossing the boundaries between dimensions. Now you perceive the very strings that make up the fabric of reality. Inperciable to all but yourself, upon pulling or thinking about pulling said strings, you may transform reality around you; however, you need to find the right strings to pull in order to get the correct effect that you wish.
Pulling upon a string connected to another human, you can alter them slowly, increasing the power that they can use, granting them powers for a short time, taking away their powers, granting them immunity to psychic attacks, or altering the age of the one whose string you have pulled. You could also use this power to heal people or even raise the dead, so long as they have recently departed.
Using this power, you could also change objects, creating new life out of existing matter, or create viewing portals that would allow you to see into alternate realities or different dimensions, or even traverse the multiverse. Transmuting matter from one state to another or even creating exact duplicates of objects or people.
The longer you use this power, the more uses you can find by pulling the right strings, gaining more control over pulling the right strings, and affecting things that are farther away from you. Eventually growing into your full potential, create pocket dimensions, and so much more.