Red magic is closely linked with satanic pacts. Black magic and red magic spells also often include blood. What is certain is that both types of magic are combined at times but do not become exactly the same, are not antagonistic as if they are white magic and black but it is wrong to consider it a branch of black magic, although it is often associated with this.
Red magic spells that work fast usually demand some sort of favor in exchange for something. Most times, a sacrifice is required from one who performs the spell. This is usually in the form of having sex before the spell, eating tissues to obtain body power or simply performing a blood sacrifice.