How to create custom interactions?

Hello!

Is it possible to create a custom interaction for an object like adding a new interaction to the list of interactions the object has or modifying the animation of an existing interaction and making it a new interaction? If it is possible, how can I do it? This is my first time with these things and either I can't find an answer or I just don't understand the answers so I had to ask here.   

I await for your kind responses. 

Thanks!