Hi, i′ve made a vampire npc, but when he sees the Pc, the vampire attacks him instantly. What should I do to make the vampire pc-friendly, so they can talk without fight? thanks!

Remove basically everything from the Vampire script except the AddSpell section, which is what gives the NPC the vampire abilities.
Be sure to make an original script.
The most basic would look something like this (untested)

Begin "name of my vamp script"short DoneIf ( MenuMode == 1 )	ReturnEndifif ( Done == 0 )	AddSpell, "Vampire Blood Quarra"		AddSpell, "Vampire Attributes"	AddSpell, "Vampire Skills"	AddSpell, "Vampire Immunities"	AddSpell, "Vampire Sun Damage"	;AddSpell, "Vampire Touch"	AddSpell, "Vampire Quarra Specials"	ModRestoration 75	set Done to 1endifif ( OnDeath == 1 )	AddItem "ingred_vampire_dust_01" 1Endifend

This gets rid of the Vampire checks, and Clan checks, and if you've been cured of Vampirism.... all of which can start combat.

Also be sure that the Fight in their AI is set to 30 or lower.

Thanks! Now the npc can talk, but, it gave me two errors:

-When iniciating MW, at loading mods screen, it says that Float script has not been compiled, what is it?
-If my pc is a vampire, the vampire npc don′t want to talk with him, because PC is a vampire, and I want him to be a vampire and talk with the pc if he es a vampire too

Thanks!!

1. In CS, open the script window, click Open and find a script Float - is its title in the list marked by an asterisk, indicating it's updated? If so (and I suppose you don't have a reason to edit it), clean it out with TESAME.
2. Make a custom greeting (or a series of greetings covering all possible situations your NPC should react to - original greetings won't be used) with NPC's name as a filter condition in a section Greeting 0 or Greeting 1. Vampire-oriented greetings are Greeting 2, so they will be precluded.