Collide Characters

I have Character 1 in left side and character 2 on right side. There is around 100 pixel space between 2 characters. On Tap I want to collide both character with speed. That means that 100 pixel space will remove. How do I achieve that?

 

Also after tap both character 1 and character 2 move to their original place. Means starting point. Thanks

 

I think I can use bullet to achieve this but on tap fire bullet how to do that?