On top of red this would probably just make your red brighter and give you a pink tint, I don't think it would turn it hot pink though. This is semi permanent color so it works best on prelightned hair :)
You are right:) lol semi permanent fades with each shampoo. Some colors you can use heat like sitting under a dryer to make them stay longer, I'm not sure about this one But I can find out from the bottle
Btw I will have more of these colors up soon so keep watching!! Going on maternity leave from the salon soon so trying to make some room in my inventory