Can I do this?
I want to know if I can mix the developer with like..Purple or something, and put it in my hair, if it'll lighten as it colors?
No, the peroxide will just bleach the colour out of the dye, direct dyes are not designed to be used this way. You need to lighten the hair first and then add the purple.
I have seen people do this online but only for hair extensions and only with adore dyes. I wouldn't recommend doing it to your own hair as you don't know how damaged your hair might get. The color itself comes out well on extensions but they do look really damaged after.
Its safer to lighten before and then color.