I invent a teleporter, something to make myself invisible and a time machine to travel to the past and i travel to 1947. When i arrive there i hide the time machine and i go to the roof of the building where the guy who tried to kill himself in the original timeline tried to do so some minutes before he arrives. When he arrives i talk to him.
Me: hey Mr sansweet do you want to kill yourself?
Guy who tried to kill himself: yes how did you know it?
Me: because i come from the future. And if you want to kill yourself i recommend you not to jump because in this timeline Mr incredible jumps to save you. But i have a solution here are some suicide pills. Take one.
Then i teleport to the floor where bomb voyage will be robbing money and i turn myself invisible, the guy takes a pill, he drinks it and dies. Mr incredible sees him falling and jumps to save him but in the process he breaks his neck's bones. Mr incredible doesn't hear his heart and panicks
Mr incredible: oh no i killed him!
Mr incredible hears something and something explodes. Bomb voyage appears in front of him
Mr incredible: bomb voyage
Bomb voyage (in french): Mr incredible!
I knock bomb voyage unconscious and i become visible
Syndrome: and incrediboy!
Mr incredible: what the…?! Where did you get this clothes?
Me: I'm from the future and in my timeline superheroes become illegal. And by the way you didn't kill that guy i gave him a pill to help him to kill himself because he sues you for preventing his suicide. I'd tell you more but i won't because you have to marry elastigirl. And by the way elastigirl's my favorite superhero in the world
Mr incredible: then thank you you made me a great favor! And I'm also jealous because you like my fianceé more than me but don't change your mind because of that!
Me: ok bye
I return to 1962 and nothing from what i did had bad consequences