First, do some research on what tropical fruits will grow well in a container and how big that container would have to be. Second, start adding artificial lighting, heat and humidity.
Remember, though, in your efforts to keep you trees small enough to fit in the living room, you may sacrifice fruit. Also, the trees will have to reach some maturity: Mangos 7-8 years from seed and Avocados 10 years. Then, there's no guarantee you will get them to produce or if the quality of the fruit will be what you hoped for.
Have fun!
